Zooming optical system, optical apparatus, and manufacturing method for the zooming optical system

ABSTRACT

A zooming optical system comprises, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power. Upon zooming, distances between adjacent lens groups of the first to the fifth lens groups change respectively. The zooming optical system further satisfies the conditional expression 9.6&lt;ft/(−f2)&lt;20.0, where ft denotes a focal length of the zooming optical system in a telephoto end state, and f2 denotes a focal length of the second lens group.

RELATED APPLICATIONS

This is a continuation of PCT International Application No.PCT/JP2014/000396, filed on Jan. 27, 2014, which is hereby incorporatedby reference. This application also claims the benefit of JapanesePatent Application Nos. 2013-012752, 2013-012753, 2013-012754,2013-012755, 2013-012756, 2013-012757 and 2013-012758 filed in Japan onJan. 28, 2013, which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a zooming optical system, an opticalapparatus and a manufacturing method for the zooming optical system.

TECHNICAL BACKGROUND

A zooming optical system suitable for a photographic cameras, electronicstill cameras, video cameras or the like has been proposed (e.g. PatentDocument 1). In recent years, requirements for preventing ghosts andflares, which would diminish optical performance, are becomingincreasingly stricter for zooming optical systems suitable forphotographic cameras, electronic still cameras, video cameras or thelike, therefore higher performance is also demanded for ananti-reflection film formed on a lens surface, and to meet this demand,multilayer film designing technology and multilayer film depositiontechnology are continuously advancing (e.g. see Patent Document 2).

PRIOR ARTS LIST Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No.2009-180844(A)

Patent Document 2: Japanese Laid-Open Patent Publication No.2000-356704(A)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

A problem of a conventional zooming optical system is that aberrationfluctuation upon zooming is considerable. Moreover, in the case of aconventional zooming optical system, reflected light that causes ghostsand flares is easily generated from optical surfaces, which affectsoptical performance.

With the foregoing in view, it is an object of the present invention toprovide a zooming optical system and an optical apparatus that ideallysuppresses aberration fluctuations upon zooming, and a manufacturingmethod for the zooming optical system.

It is another object of the present invention to provide a zoomingoptical system and an optical apparatus having a high opticalperformance to further decrease ghosts and flares, while ideallysuppressing aberration fluctuations upon zooming, and a manufacturingmethod for the zooming optical system.

Means to Solve the Problems

To solve the above problems, a zooming optical system according to afirst aspect of the present invention is constituted by, in order froman object: a first lens group having positive refractive power; a secondlens group having negative refractive power; a third lens group havingpositive refractive power; a fourth lens group having negativerefractive power; and a fifth lens group having positive refractivepower, and in this zooming optical system, the first lens group is movedalong the optical axis upon zooming, at least a part of the second lensgroup to the fifth lens group being moved so as to include a componentorthogonal to the optical axis, and the following conditionalexpressions are satisfied:

4.41<f1/(−f2)<5.33

2.15<f1/f3<4.95

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, and f3 denotes a focal length ofthe third lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.18<f3/(−f4)<0.92

where f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.82<(−f4)/f5<1.58

where f4 denotes a focal length of the fourth lens group, and f5 denotesa focal length of the fifth lens group.

In this zooming optical system, it is preferable that an aperture stopis disposed in a position closer to the image than the second lensgroup.

In this zooming optical system, it is preferable that an aperture stopis disposed in a position between the third lens group and the fifthlens group.

In this zooming optical system, it is preferable that an aperture stopis disposed in a position between the third lens group and the fourthlens group.

In this zooming optical system, it is preferable that at least a part ofthe third lens group is moved along the optical axis upon focusing.

In this zooming optical system, it is preferable that a second lensgroup is fixed with respect to the image plane upon zooming.

In this zooming optical system, it is preferable that at least a part ofthe second lens group is moved so as to include a component orthogonalto the optical axis.

In this zooming optical system, it is preferable that all the lenssurfaces are spherical.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.10<f3/f5<1.06

where f5 denotes a focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.70<f1/(−f4)<2.55

where f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.11<f2/f4<0.62

where f2 denotes a focal length of the second lens group, and f4 denotesa focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

9.6<ft/(−f2)<20.0

where ft denotes a focal length of the zooming optical system in atelephoto end state.

In the zooming optical system, it is preferable that the followingconditional expression is satisfied:

3.9<ft/(−f4)<8.8

where ft denotes a focal length of the zooming optical system in thetelephoto end state, and f4 denotes a focal length of the fourth lensgroup.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.8<(−f4)/f5<1.8

where f4 denotes a focal length of the fourth lens group, and f5 denotesa focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.3<(−f2)/f5<0.8

where f5 denotes a focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

1.3<f1/(−f4)<3.0

where f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

1.9<f1/f5<3.2

where f5 denotes a focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.32<(−f4)/f5<1.93

where f4 denotes a focal length of the fourth lens group, and f5 denotesa focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.74<f1/(−f4)<2.82

where f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.44<(−f2)/f3<0.86.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.32<(−f4)/f5<2.07

where f4 denotes a focal length of the fourth lens group, and f5 denotesa focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.29<f3/(−f4)<0.87

where f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that an anti-reflectionfilm including at least one layer formed by a wet process is formed onat least one surface of the optical surfaces.

It is preferable that the anti-reflection film is a multilayer film, andthe outermost layer of the multilayer film is a layer formed by the wetprocess.

It is more preferable that the following conditional expression issatisfied:

nd≤1.30

where nd denotes a refractive index at d-line of the layer formed by thewet process.

An optical apparatus according to the first aspect of the presentinvention includes this zooming optical system for forming an objectimage on a predetermined image plane.

A zooming optical system according to a second aspect of the presentinvention is constituted by, in order from an object: a first lens grouphaving positive refractive power; a second lens group having negativerefractive power; a third lens group having positive refractive power; afourth lens group having negative refractive power; and a fifth lensgroup having positive refractive power, and in this zooming opticalsystem, the first lens group is moved along the optical axis uponzooming, at least a part of the second lens group to the fifth lensgroup is moved so as to include a component orthogonal to the opticalaxis, and the following conditional expressions being satisfied:

4.41<f1/(−f2)<5.33

0.10<f3/f5<1.06

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, f3 denotes a focal length of thethird lens group, and f5 denotes a focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied: 0.70<f1/(−f4)<2.55 where f4 denotesa focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.11<f2/f4<0.62

where f4 denotes a focal length of the fourth lens group.

An optical apparatus according to the second aspect of the presentinvention includes the zooming optical system according to the secondaspect of the present invention for forming an object image on apredetermined image plane.

A zooming optical system according to a third aspect of the presentinvention is constituted by, in order from an object: a first lens grouphaving positive refractive power; a second lens group having negativerefractive power; a third lens group having positive refractive power; afourth lens group having negative refractive power; and a fifth lensgroup having positive refractive power, and in this zooming opticalsystem, the second lens group is fixed with respect to the image planeupon zooming, and the following conditional expressions are satisfied:

9.6<ft/(−f2)<20.0

3.9<ft/(−f4)<8.8

where ft denotes a focal length of the zooming optical system in atelephoto end state, f2 denotes a focal length of the second lens group,and f4 denotes a focal length of the fourth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.8<(−f4)/f5<1.8

where f5 denotes a focal length of the fifth lens group.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.3<(−f2)/f5<0.8

where f5 denotes a focal length of the fifth lens group.

An optical apparatus according to the third aspect of the presentinvention includes the zooming optical system according to the thirdaspect of the present invention for forming an object image on apredetermined image plane.

A zooming optical system according to a fourth aspect of the presentinvention is constituted by, in order from the object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, and in this zooming opticalsystem, the second lens group is fixed with respect to the image planeupon zooming, and the following conditional expressions are satisfied:

2.0<f1/(−f2)<6.1

1.3<f1/(−f4)<3.0

1.9<f1/f5<3.2

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.8<(−f4)/f5<1.8.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.3<(−f2)/f5<0.8.

An optical apparatus according to the fourth aspect of the presentinvention includes the zooming optical system according to the fourthaspect of the present invention for forming an object image on apredetermined image plane.

A zooming optical system according to the fifth aspect of the presentinvention is constituted by, in order from an object: a first lens grouphaving positive refractive power; a second lens group having negativerefractive power; a third lens group having positive refractive power; afourth lens group having negative refractive power; and a fifth lensgroup having positive refractive power, and in this zooming opticalsystem, the second lens group and the fourth lens group are fixed withrespect to the image plane upon zooming, and the following conditionalexpressions are satisfied:

1.05<f1/(−f2)<6.10

0.32<(−f4)/f5<1.93

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.74<f1/(−f4)<2.82.

An optical apparatus according to the fifth aspect of the presentinvention includes the zooming optical system according to the fifthaspect of the present invention for forming an object image on apredetermined image plane.

A zooming optical system according to a sixth aspect of the presentinvention is constituted by, in order from an object: a first lens grouphaving positive refractive power; a second lens group having negativerefractive power; a third lens group having positive refractive power; afourth lens group having negative refractive power; and a fifth lensgroup having positive refractive power, and in this zooming opticalsystem, the second lens group and the fourth lens group are fixed withrespect to the image plane upon zooming, and the following conditionalexpressions are satisfied:

0.44<(−f2)/f3<0.86

0.32<(−f4)/f5<2.07

where f2 denotes a focal length of the second lens group, f3 denotes afocal length of the third lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

In this zooming optical system, it is preferable that the followingconditional expression is satisfied:

0.29<f3/(−f4)<0.87.

An optical apparatus according to the sixth aspect of the presentinvention includes the zooming optical system according to the sixthaspect of the present invention for forming an object image on apredetermined image plane.

A manufacturing method for a zooming optical system according to a firstaspect of the present invention is a manufacturing method for a zoomingoptical system constituted by, in order from an object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including:disposing the first lens group to move along the optical axis uponzooming; disposing the second lens group to the fifth lens group so thatat least a part of the second lens group to the fifth lens group move soas to include a component orthogonal to the optical axis, and thefollowing conditional expressions are satisfied:

4.41<f1/(−f2)<5.33

2.15<f1/f3<4.95

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, and f3 denotes a focal length ofthe third lens group.

A manufacturing method for a zooming optical system according to asecond aspect of the present invention is a manufacturing method for azooming optical system constituted by, in order from an object: a firstlens group having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including:disposing the first lens group to move along the optical axis uponzooming; disposing the second lens group to the fifth lens group so thatat least a part of the second lens group to the fifth lens group move soas to include a component orthogonal to the optical axis, and thefollowing conditional expressions are satisfied:

4.41<f1/(−f2)<5.33

0.10<f3/f5<1.06

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, and f3 denotes a focal length ofthe third lens group, and f5 denotes a focal length of the fifth lensgroup.

A manufacturing method for a zooming optical system according to a thirdaspect of the present invention is a manufacturing method for a zoomingoptical system constituted by, in order from an object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including;disposing the second lens group to be fixed with respect to the imageplane upon zooming, and the following conditional expressions beingsatisfied:

9.6<ft/(−f2)<20.0

3.9<ft/(−f4)<8.8

where ft denotes a focal length of the zooming optical system in atelephoto end state, f2 denotes a focal length of the second lens group,and f4 denotes a focal length of the fourth lens group.

A manufacturing method for a zooming optical system according to afourth aspect of the present invention is a manufacturing method for azooming optical system constituted by, in order from an object: a firstlens group having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including:disposing the second lens group to be fixed with respect to the imageplane upon zooming, and the following conditional expressions beingsatisfied:

2.0<f1/(−f2)<6.1

1.3<f1/(−f4)<3.0

1.9<f1/f5<3.2

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

A manufacturing method for a zooming optical system according to a fifthaspect of the present invention is a manufacturing method for a zoomingoptical system constituted by, in order from an object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including:disposing the second lens group and the fourth lens group to be fixedwith respect to the image plane upon zooming, and the followingconditional expressions being satisfied:

1.05<f1/(−f2)<6.10

0.32<(−f4)/f5<1.93

where f1 denotes a focal length of the first lens group, f2 denotes afocal length of the second lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

A manufacturing method for a zooming optical system according to a sixthaspect of the present invention is a manufacturing method for a zoomingoptical system constituted by, in order from an object: a first lensgroup having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, the method including:disposing the second lens group and the fourth lens group to be fixedwith respect to the image plane upon zooming, and the followingconditional expressions being satisfied:

0.44<(−f2)/f3<0.86

0.32<(−f4)/f5<2.07

where f2 denotes a focal length of the second lens group, f3 denotes afocal length of the third lens group, f4 denotes a focal length of thefourth lens group, and f5 denotes a focal length of the fifth lensgroup.

Advantageous Effects of the Invention

According to the present invention, a zooming optical system and anoptical apparatus that ideally suppresses aberration fluctuations uponzooming, and a manufacturing method for the zooming optical system, canbe provided.

According to another aspect of the present invention, a zooming opticalsystem and an optical apparatus having a high optical performance tofurther decrease ghosts and flares while ideally suppressing aberrationfluctuations upon zooming, and a manufacturing method for the zoomingoptical system, can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view depicting a lens configuration of azooming optical system according to Example 1;

FIGS. 2A and 2B are sets of graphs showing various aberrations of thezooming optical system according to Example 1 in the wide-angle endstate, where FIG. 2A shows various aberrations in the infinity focusingstate, and FIG. 2B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIGS. 3A and 3B are sets of graphs showing various aberrations of thezooming optical system according to Example 1 in the intermediate focallength state, where FIG. 3A shows various aberrations in the infinityfocusing state, and FIG. 3B shows coma aberrations when image blur iscorrected in the infinity focusing state;

FIGS. 4A and 4B are sets of graphs showing various aberrations of thezooming optical system according to Example 1 in the telephoto endstate, where FIG. 4A shows various aberrations in the infinity focusingstate, and FIG. 4B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIG. 5 is a diagram depicting a state of the incident rays reflecting onthe first ghost generation plane and the second ghost generation planein the zooming optical system according to Example 1;

FIG. 6 is a cross-sectional view depicting a lens configuration of azooming optical system according to Example 2;

FIGS. 7A and 7B are sets of graphs showing various aberrations of thezooming optical system according to Example 2 in the wide-angle endstate, where FIG. 7A shows various aberrations in the infinity focusingstate, and FIG. 7B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIGS. 8A and 8B are sets of graphs showing various aberrations of thezooming optical system according to Example 2 in the intermediate focallength state, where FIG. 8A shows various aberrations in the infinityfocusing state, and FIG. 8B shows coma aberrations when image blur iscorrected in the infinity focusing state;

FIGS. 9A and 9B are sets of graphs showing various aberrations of thezooming optical system according to Example 2 in the telephoto endstate, where FIG. 9A shows various aberrations in the infinity focusingstate, and FIG. 9B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIG. 10 is a cross-sectional view depicting a lens configuration of azooming optical system according to Example 3;

FIGS. 11A and 11B are sets of graphs showing various aberrations of thezooming optical system according to Example 3 in the wide-angle endstate, where FIG. 11A shows various aberrations in the infinity focusingstate, and FIG. 11B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIGS. 12A and 12B are sets of graphs showing various aberrations of thezooming optical system according to Example 3 in the intermediate focallength state, where FIG. 12A shows various aberrations in the infinityfocusing state, and FIG. 12B shows coma aberrations when image blur iscorrected in the infinity focusing state;

FIGS. 13A and 13B are sets of graphs showing various aberrations of thezooming optical system according to Example 3 in the telephoto endstate, where FIG. 13A shows various aberrations in the infinity focusingstate, and FIG. 13B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIG. 14 is a cross-sectional view depicting a lens configuration of azooming optical system according to Example 4;

FIGS. 15A and 15B are sets of graphs showing various aberrations of thezooming optical system according to Example 4 in the wide-angle endstate, where FIG. 15A shows various aberrations in the infinity focusingstate, and FIG. 15B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIGS. 16A and 16B are sets of graphs showing various aberrations of thezooming optical system according to Example 4 in the intermediate focallength state, where FIG. 16A shows various aberrations in the infinityfocusing state, and FIG. 16B shows coma aberrations when image blur iscorrected in the infinity focusing state;

FIGS. 17A and 17B are sets of graphs showing various aberrations of thezooming optical system according to Example 4 in the telephoto endstate, where FIG. 17A shows various aberrations in the infinity focusingstate, and FIG. 17B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIG. 18 is a cross-sectional view depicting a lens configuration of azooming optical system according to Example 5;

FIGS. 19A and 19B are sets of graphs showing various aberrations of thezooming optical system according to Example 5 in the wide-angle endstate, where FIG. 19A shows various aberrations in the infinity focusingstate, and FIG. 19B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIGS. 20A and 20B are sets of graphs showing various aberrations of thezooming optical system according to Example 5 in the intermediate focallength state, where FIG. 20A shows various aberrations in the infinityfocusing state, and FIG. 20B shows coma aberrations when image blur iscorrected in the infinity focusing state;

FIGS. 21A and 21B are sets of graphs showing various aberrations of thezooming optical system according to Example 5 in the telephoto endstate, where FIG. 21A shows various aberrations in the infinity focusingstate, and FIG. 21B shows coma aberrations when image blur is correctedin the infinity focusing state;

FIG. 22 is a cross-sectional view of a camera in which the zoomingoptical system is mounted;

FIG. 23 is a flow chart depicting a manufacturing method for the zoomingoptical system;

FIG. 24 is a flow chart depicting another manufacturing method for thezooming optical system;

FIG. 25 is a flow chart depicting still another manufacturing method forthe zooming optical system;

FIG. 26 is a diagram depicting a structure of an anti-reflection filmaccording to the example;

FIG. 27 is a graph depicting a spectral characteristic of theanti-reflection film according to the example;

FIG. 28 is a graph depicting a spectral characteristic of theanti-reflection film according to a modification;

FIG. 29 is a graph depicting a spectral characteristic of theanti-reflection film according to a modification;

FIG. 30 is a graph depicting a spectral characteristic of ananti-reflection film formed by a prior art; and

FIG. 31 is a graph depicting a spectral characteristic of ananti-reflection film formed by a prior art.

DESCRIPTION OF THE EMBODIMENTS

Preferable embodiments of the present invention will now be describedwith reference to the drawings. As shown in FIG. 1, a zooming opticalsystem ZL according to the present invention is constituted by, in orderfrom the object: a first lens group G1 having positive refractive power;a second lens group G2 having negative refractive power; a third lensgroup G3 having positive refractive power; a fourth lens group G4 havingnegative refractive power; and a fifth lens group G5 having positiverefractive power. In this zooming optical system ZL, it is preferablethat the first lens group G1 is moved toward the image plane I along theoptical axis upon zooming. By this configuration, aberration fluctuationduring zooming can be decreased. Moreover, the refractive power of thefirst lens group G1 can be weakened, hence a worsening of aberrations,when decentering is generated due to manufacturing error, can becontrolled.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

Conditions to construct this zooming optical system ZL will now bedescribed. It is preferable that the zooming optical system ZL satisfiesthe following conditional expression (1).

4.41<f1/(−f2)<5.33  (1)

where f1 denotes a focal length of the first lens group G1, and f2denotes a focal length of the second lens group G2.

The conditional expression (1) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the secondlens group G2. By satisfying the conditional expression (1), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(1) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (1) is4.45, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (1) isexceeded, the refractive power of the first lens group G1 decreases andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (1) is5.30, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (2) is satisfied.

2.15<f1/f3<4.95  (2)

where f1 denotes a focal length of the first lens group G1, and f3denotes a focal length of the third lens group G3.

The conditional expression (2) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the thirdlens group G3. By satisfying the conditional expression (2), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(2) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (2) is2.20, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (2) isexceeded, the refractive power of the first lens group G1 decreases, andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (2) is4.35, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (3) is satisfied.

0.18<f3/(−f4)<0.92  (3)

where f3 denotes a focal length of the third lens group G3, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (3) specifies an appropriate focal length ofthe third lens group G3 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (3), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(3) is not reached, the refractive power of the third lens group G3increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (3) is0.22, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (3) isexceeded, the refractive power of the third lens group G3 decreases, andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (3) is0.85, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (4) is satisfied.

0.82<(−f4)/f5<1.58  (4)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (4) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (4), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (4) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (4) is 0.88, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (4) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(4) is 1.52, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that the second lensgroup G2 is fixed with respect to the image plane I upon zooming. Bythis configuration, the lens barrel configuration during zooming can besimplified, and the size of the lens barrel can be smaller. Further,deterioration of optical performance, due to manufacturing error, can becontrolled.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to this embodiment will be described with reference to FIG.23. First the lens groups G1 to G5 are prepared by disposing each lens(step S100). Each lens group is disposed so that the first lens group G1is moved along the optical axis upon zooming (step S200). Further, eachlens group is disposed so that at least a part of the second lens groupG2 to the fifth lens group G5 is moved so as to include a componentorthogonal to the optical axis (step S300). Furthermore, each lens groupG1 to G5 is disposed so that each lens group G1 to G5 satisfies theabove mentioned conditional expressions (1) and (2) (step S400).

In concrete terms, as shown in FIG. 1 for example, the first lens groupG1 is created by disposing, in order from the object: a cemented lens(in which a negative meniscus lens L11 having a convex surface facingthe object and a biconvex lens L12 are cemented), and a positivemeniscus lens L13 having a convex surface facing the object; the secondlens group G2 is created by disposing a cemented lens (in which abiconvex lens L21 and a biconcave lens L22 are cemented), a cementedlens (in which a biconcave lens L23 and a positive meniscus lens L24having a convex surface facing the object are cemented), and a biconcavelens L25; the third lens group G3 is created by disposing a biconvexlens L31, and a cemented lens (in which a negative meniscus lens L32having a convex surface facing the object and a biconvex lens L33 arecemented); the fourth lens group G4 is created by disposing a cementedlens, (in which a biconcave lens L41 and a positive meniscus lens L42having the convex surfaces facing the object are cemented); and thefifth lens group G5 is created by disposing a biconvex lens L51, acemented lens, (in which a plano-convex lens L52 having a convex surfacefacing the object, a plano-concave lens L53 having a concave surfacefacing the image, and a plano-convex lens L54 having a convex surfacefacing the object are cemented), a cemented lens, (in which a biconvexlens L55 and a plano-concave lens L56 having a concave surface facingthe object are cemented), and a negative meniscus lens L57 having aconcave surface facing the object. Each lens group prepared like this isdisposed according to the above mentioned procedure, whereby the zoomingoptical system ZL is manufactured.

A second preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the second preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the first lens group G1 ismoved toward the image plane I along the optical axis upon zooming. Bythis configuration, aberration fluctuation during zooming can bedecreased. Moreover, the refractive power of the first lens group G1 canbe weakened, hence a worsening of aberrations, when decentering isgenerated due to manufacturing error, can be controlled.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

Conditions to construct the zooming optical system ZL according to thesecond preferred embodiment will now be described. It is preferable thatthe zooming optical system ZL satisfies the following conditionalexpression (5).

4.41<f1/(−f2)<5.33  (5)

where f1 denotes a focal length of the first lens group G1, and f2denotes a focal length of the second lens group G2.

The conditional expression (5) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the secondlens group G2. By satisfying the conditional expression (5), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(5) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (5) is4.45, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (5) isexceeded, the refractive power of the first lens group G1 decreases andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (5) is5.30, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (6) is satisfied.

0.10<f3/f5<1.06  (6)

where f3 denotes a focal length of the third lens group G3, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (6) specifies an appropriate focal length ofthe third lens group G3 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (6), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(6) is not reached, the refractive power of the third lens group G3increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (6) is0.24, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (6) isexceeded, the refractive power of the third lens group G3 decreases, andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (6) is1.00, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (7) is satisfied.

0.70<f1/(−f4)<2.55  (7)

where f1 denotes a focal length of the first lens group G1, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (7) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (7), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(7) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (7) is0.77, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (7) isexceeded, the refractive power of the first lens group G1 decreases, andthe total length of the zooming optical system increases, which is notdesirable. If the upper limit value of the conditional expression (7) is2.45, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (8) is satisfied.

0.11<f2/f4<0.62  (8)

where f2 denotes a focal length of the second lens group G2, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (8) specifies an appropriate focal length ofthe second lens group G2 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (8), comaaberration in the wide-angle end state and chromatic aberration in thetelephoto end state can be corrected well. If the lower limit value ofthe conditional expression (8) is not reached, the refractive power ofthe second lens group G2 increases, and correction of coma aberration inthe wide-angle end state becomes difficult, which is not desirable. Ifthe lower limit value of the conditional expression (8) is 0.14, theeffect of the present application can be demonstrated with certainty. Ifthe upper limit value of the conditional expression (8) is exceeded, therefractive power of the fourth lens group G4 increases, and correctionof the Chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the upper limit value of theconditional expression (8) is 0.55, the effect of the presentapplication can be demonstrated with certainty.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that the second lensgroup G2 is fixed with respect to the image plane I upon zooming. Bythis configuration, the lens barrel configuration during zooming can besimplified, and the size of the lens barrel can be smaller. Further,deterioration of optical performance, due to manufacturing error, can becontrolled.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to a second embodiment will be described with reference toFIG. 23. First the lens groups G1 to G5 are prepared by disposing eachlens (step S100). Each lens group is disposed so that the first lensgroup G1 is moved along the optical axis upon zooming (step S200).Further, each lens group G1 to G5 is disposed so that at least a part ofthe second lens group G2 to the fifth lens group G5 is moved so as toinclude a component orthogonal to the optical axis (step S300).Furthermore, each lens group is disposed so that each lens group G1 toG5 satisfies the above mentioned conditional expressions (5) and (6)(step S400).

In concrete terms, as shown in FIG. 1 for example, the first lens groupG1 is created by disposing, in order from the object: a cemented lens(in which a negative meniscus lens L11 having a convex surface facingthe object and a biconvex lens L12 are cemented), and a positivemeniscus lens L13 having a convex surface facing the object; the secondlens group G2 is created by disposing a cemented lens (in which abiconvex lens L21 and a biconcave lens L22 are cemented), and a cementedlens (in which a biconcave lens L23 and a positive meniscus lens L24having a convex surface facing the object are cemented), and a biconcavelens L25; the third lens group G3 is created by disposing a biconvexlens L31, and a cemented lens (in which a negative meniscus lens L32having a convex surface facing the object and a biconvex lens L33 arecemented); the fourth lens group G4 is created by disposing a cementedlens (in which a biconcave lens L41 and a positive meniscus lens L42having the convex surfaces facing the object are cemented); and thefifth lens group G5 is created by disposing a biconvex lens L51, acemented lens (in which a plano-convex lens L52 having a convex surfacefacing the object, a plano-concave lens L53 having a concave surfacefacing the image, and a plano-convex lens L54 having a convex surfacefacing the object are cemented), a cemented lens (in which a biconvexlens L55 and a plano-concave lens L56 having a concave surface facingthe object are cemented), and a negative meniscus lens L57 having aconcave surface facing the object. Each lens group prepared like this isdisposed according to the above mentioned procedure, whereby the zoomingoptical system ZL is manufactured.

A third preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the third preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the second lens group G2 isfixed with respect to the image plane upon zooming. By thisconfiguration, the moving distance of each lens group upon zooming canbe decreased. Fixing the second lens group G2 can also minimize theinfluence of decentering due to manufacturing error.

Conditions to construct the zooming optical system ZL according to thethird preferred embodiment will now be described. It is preferable thatthe zooming optical system ZL satisfies the following conditionalexpression (9).

9.6<ft/(−f2)<20.0  (9)

where ft denotes a focal length of the zooming optical system in thetelephoto end state, and f2 denotes a focal length of the second lensgroup G2.

The conditional expression (9) specifies an appropriate focal length ofthe second lens group G2 with respect to the focal length of the entiresystem of the zooming optical system ZL in the telephoto end state. Bysatisfying the conditional expression (9), coma aberration in thewide-angle end state can be corrected favorably. If the lower limitvalue of the conditional expression (9) is not reached, the refractivepower of the second lens group G2 increases, and correction of comaaberration in the wide-angle end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (9) is10.0, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (9) isexceeded, the refractive power of the second lens group G2 decreases,and the diameter of the first lens group G1 increases, and decreasingthe size of the lens barrel becomes difficult, which is not desirable.If the upper limit value of the conditional expression (9) is 18.0, theeffect of the present application can be demonstrated with certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (10) is satisfied.

3.9<ft/(−f4)<8.8  (10)

where ft denotes a focal length of the zooming optical system in thetelephoto end state, and f4 denotes a focal length of the fourth lensgroup G4.

The conditional expression (10) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the entiresystem of the zooming optical system ZL in the telephoto end state. Bysatisfying the conditional expression (10), spherical aberration andchromatic aberration in the telephoto end state can be corrected well.If the lower limit value of the conditional expression (10) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not preferable. If the lower limit value of theconditional expression (10) is 4.0, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (10) is exceeded, the refractive power ofthe fourth lens group G4 decreases, and shortening of the total lengthof the zooming optical system ZL becomes difficult, which is notdesirable. If the upper limit value of the conditional expression (10)is 8.0, the effect of the present application can be demonstrated withcertainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (11) is satisfied.

0.8<(−f4)/f5<1.8  (11)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (11) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (11), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (11) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (11) is 0.9, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (11) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(11) is 1.6, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (12) is satisfied.

0.3<(−f2)/f5<0.8  (12)

where f2 denotes a focal length of the second lens group G2, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (12) specifies an appropriate focal length ofthe second lens group G2 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (12), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (12) is notreached, the refractive power of the second lens group G2 increases, andcorrection of coma aberration in the wide-angle end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (12) is 0.4, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (12) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(12) is 0.7, the effect of the present application can be demonstratedwith certainty. If the upper limit value of the conditional expression(12) is 0.6, the effect of the present application can be demonstratedat the maximum.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to the third embodiment will be described with reference toFIG. 24. First the lens groups G1 to G5 are prepared by disposing eachlens (step S100). Each lens group is disposed so that the second lensgroup G2 is fixed with respect to the image plane I upon zooming (stepS200). Further, each lens group G1 to G5 is disposed so that theconditional expressions (9) and (10) are satisfied (step S300).

In concrete terms, in the present embodiment as shown in FIG. 1 forexample, the first lens group G1 is created by disposing, in order fromthe object: a cemented lens (in which a negative meniscus lens L11having a convex surface facing the object and a biconvex lens L12 arecemented), and a positive meniscus lens L13 having a convex surfacefacing the object; the second lens group G2 is created by disposing acemented lens (in which a biconvex lens L21 and a biconcave lens L22 arecemented), a cemented lens (in which a biconcave lens L23 and a positivemeniscus lens L24 having a convex surface facing the object arecemented), and a biconcave lens L25; the third lens group G3 is createdby disposing a biconvex lens L31, and a cemented lens (in which anegative meniscus lens L32 having a convex surface facing the object anda biconvex lens L33 are cemented); the fourth lens group G4 is createdby disposing a cemented lens (in which a biconcave lens L41 and apositive meniscus lens L42 having the convex surfaces facing the objectare cemented); and the fifth lens group G5 is created by disposing abiconvex lens L51, a cemented lens (in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented), a cemented lens(in which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented), and a negative meniscuslens L57 having a concave surface facing the object. Each lens groupprepared like this is disposed according to the above mentionedprocedure, whereby the zooming optical system ZL is manufactured.

A fourth preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the fourth preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the second lens group G2 isfixed with respect to the image plane upon zooming. By thisconfiguration, the moving distance of each lens group upon zooming canbe decreased. Fixing the second lens group G2 can also minimize theinfluence of decentering due to manufacturing error.

Conditions to construct the zooming optical system ZL according to thefourth preferred embodiment will now be described. It is preferable thatthe zooming optical system ZL satisfies the following conditionalexpression (13).

2.0<f1/(−f2)<6.1  (13)

where f1 denotes a focal length of the first lens group G1, and f2denotes a focal length of the second lens group G2.

The conditional expression (13) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the secondlens group G2. By satisfying the conditional expression (13), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(13) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (13)is 3.0, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (13)is exceeded, the refractive power of the first lens group G1 decreasesand the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(13) is 6.0, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (14) is satisfied.

1.3<f1/(−f4)<3.0  (14)

where f1 denotes a focal length of the first lens group G1, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (14) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (14), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(14) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (14)is 1.4, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (14)is exceeded, the refractive power of the first lens group G1 decreases,and the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(14) is 2.8, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (15) is satisfied.

1.9<f1/f5<3.2  (15)

where f1 denotes a focal length of the first lens group G1, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (15) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (15), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(15) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state become difficult, which is notdesirable. If the lower limit value of the conditional expression (15)is 2.0, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (15)is exceeded, the refractive power of the fifth lens group G5 increases,and correction of curvature of field and distortion in the wide-angleend state becomes difficult, which is not desirable. If the upper limitvalue of the conditional expression (15) is 3.0, the effect of thepresent application can be demonstrated with certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (16) is satisfied.

0.8<(−f4)/f5<1.8  (16)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (16) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (16), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (16) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (16) is 0.9, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (16) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(16) is 1.6, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (17) is satisfied.

0.3<(−f2)/f5<0.8  (17)

where f2 denotes a focal length of the second lens group G2, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (17) specifies an appropriate focal length ofthe second lens group G2 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (17), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (17) is notreached, the refractive power of the second lens group G2 increases, andcorrection of coma aberration in the wide-angle end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (17) is 0.4, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (17) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(17) is 0.7, the effect of the present application can be demonstratedwith certainty. If the upper limit value of the conditional expression(17) is 0.6, the effect of the present application can be demonstratedat the maximum.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to the fourth embodiment will be described with referenceto FIG. 24. First the lens groups G1 to G5 are prepared by disposingeach lens (step S100). Each lens group is disposed so that the secondlens group G2 is fixed with respect to the image plane I upon zooming(step S200). Further, each lens group G1 to G5 is disposed so that theconditional expressions (13) and (14) are satisfied (step S300).

In concrete terms, in the present embodiment as shown in FIG. 1 forexample, the first lens group G1 is created by disposing, in order fromthe object: a cemented lens (in which a negative meniscus lens L11having a convex surface facing the object and a biconvex lens L12 arecemented), and a positive meniscus lens L13 having a convex surfacefacing the object; the second lens group G2 is created by disposing acemented lens (in which a biconvex lens L21 and a biconcave lens L22 arecemented), a cemented lens (in which a biconcave lens L23 and a positivemeniscus lens L24 having a convex surface facing the object arecemented), and a biconcave lens L25; the third lens group G3 is createdby disposing a biconvex lens L31, and a cemented lens (in which anegative meniscus lens L32 having a convex surface facing the object anda biconvex lens L33 are cemented); the fourth lens group G4 is createdby disposing a cemented lens (in which a biconcave lens L41 and apositive meniscus lens L42 having the convex surfaces facing the objectare cemented); and the fifth lens group G5 is created by disposing abiconvex lens L51, a cemented lens (in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented), a cemented lens(in which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented), and a negative meniscuslens L57 having a concave surface facing the object. Each lens groupprepared like this is disposed according to the above mentionedprocedure, whereby the zooming optical system ZL is manufactured.

A fifth preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the fifth preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the second lens group G2 andthe fourth lens group G4 are fixed with respect to the image plane uponzooming. By this configuration, lens barrel configuration upon zoomingcan be simplified, and the size of the lens barrel can be smaller.Further, deterioration of optical performance, due to manufacturingerror, can be controlled.

Conditions to construct the zooming optical system ZL according to thefifth preferred embodiment will now be described. It is preferable thatthe zooming optical system ZL satisfies the following conditionalexpression (18).

1.05<f1/(−f2)<6.10  (18)

where f1 denotes a focal length of the first lens group G1, and f2denotes a focal length of the second lens group G2.

The conditional expression (18) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the secondlens group G2. By satisfying the conditional expression (18), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(18) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (18)is 2.25, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (18)is exceeded, the refractive power of the first lens group G1 decreasesand the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(18) is 5.87, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (19) is satisfied.

0.32<(−f4)/f5<1.93  (19)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (19) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (19), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (19) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (19) is 0.44, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (19) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(19) is 1.63, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (20) is satisfied.

0.74<f1/(−f4)<2.82  (20)

where f1 denotes a focal length of the first lens group G1, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (20) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (20), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(20) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (20)is 0.79, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (20)is exceeded, the refractive power of the first lens group G1 decreases,and the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(20) is 2.71, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to the fifth embodiment will be described with reference toFIG. 25. First the lens groups G1 to G5 are prepared by disposing eachlens (step S100). Each lens group is disposed so that the second lensgroup G2 and the fourth lens group G4 are fixed with respect to theimage plane I upon zooming (step S200). Further, each lens group G1 toG5 is disposed so that the conditional expressions (18) and (19) aresatisfied (step S300).

In concrete terms, in the present embodiment as shown in FIG. 1 forexample, the first lens group G1 is created by disposing, in order fromthe object: a cemented lens (in which a negative meniscus lens L11having a convex surface facing the object and a biconvex lens L12 arecemented), and a positive meniscus lens L13 having a convex surfacefacing the object; the second lens group G2 is created by disposing acemented lens (in which a biconvex lens L21 and a biconcave lens L22 arecemented), a cemented lens (in which a biconcave lens L23 and a positivemeniscus lens L24 having a convex surface facing the object arecemented), and a biconcave lens L25; the third lens group G3 is createdby disposing a biconvex lens L31, and a cemented lens (in which anegative meniscus lens L32 having a convex surface facing the object anda biconvex lens L33 are cemented); the fourth lens group G4 is createdby disposing a cemented lens (in which a biconcave lens L41 and apositive meniscus lens L42 having the convex surfaces facing the objectare cemented); and the fifth lens group G5 is created by disposing abiconvex lens L51, a cemented lens (in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented), a cemented lens(in which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented), and a negative meniscuslens L57 having a concave surface facing the object. Each lens groupprepared like this is disposed according to the above mentionedprocedure, whereby the zooming optical system ZL is manufactured.

A sixth preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the sixth preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the second lens group G2 andthe fourth lens group G4 are fixed with respect to the image plane uponzooming. By this configuration, lens barrel configuration upon zoomingcan be simplified, and the size of the lens barrel can be smaller.Further, deterioration of optical performance, due to manufacturingerror, can be controlled.

In the zooming optical system ZL according to the sixth preferredembodiment, first of all it is preferable that the following conditionalexpression (21) is satisfied for this zooming optical system ZL.

0.44<(−f2)/f3<0.86  (21)

where f2 denotes a focal length of the second lens group G2, and f3denotes a focal length of the third lens group G3.

The conditional expression (21) specifies an appropriate focal length ofthe second lens group G2 with respect to the focal length of the thirdlens group G3. By satisfying the conditional expression (21), comaaberration in the wide-angle end state and spherical aberration andchromatic aberration in the telephoto end state can be corrected well.If the lower limit value of the conditional expression (21) is notreached, the refractive power of the second lens group G2 increases, andcorrection of coma aberration in the wide-angle end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (21) is 0.47, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (21) is exceeded, the refractive power ofthe third lens group G3 increases, and correction of sphericalaberration and chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the upper limit value of theconditional expression (21) is 0.76, the effect of the presentapplication can be demonstrated with certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (22) is satisfied.

0.32<(−f4)/f5<2.07  (22)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (22) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (22), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (22) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (22) is 0.44, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (22) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(22) is 1.63, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (23) is satisfied.

0.29<f3/(−f4)<0.87  (23)

where f3 denotes a focal length of the third lens group G3, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (23) specifies an appropriate focal length ofthe third lens group G3 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (23), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(23) is not reached, the refractive power of the third lens group G3increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (23)is 0.31, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (23)is exceeded, the refractive power of the third lens group G3 decreases,and the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(23) is 0.83, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

An overview of the manufacturing method for the zooming optical systemZL according to the sixth embodiment will be described with reference toFIG. 25. First the lens groups G1 to G5 are prepared by disposing eachlens (step S100). Each lens group is disposed so that the second lensgroup G2 and the fourth lens group G4 are fixed with respect to theimage plane I upon zooming (step S200). Further, each lens group G1 toG5 is disposed so that the conditional expressions (21) and (22) aresatisfied (step S300).

In concrete terms, in the present embodiment as shown in FIG. 1 forexample, the first lens group G1 is created by disposing, in order fromthe object: a cemented lens (in which a negative meniscus lens L11having a convex surface facing the object and a biconvex lens L12 arecemented), and a positive meniscus lens L13 having a convex surfacefacing the object; the second lens group G2 is created by disposing acemented lens (in which a biconvex lens L21 and a biconcave lens L22 arecemented), a cemented lens (in which a biconcave lens L23 and a positivemeniscus lens L24 having a convex surface facing the object arecemented), and a biconcave lens L25; the third lens group G3 is createdby disposing a biconvex lens L31, and a cemented lens (in which anegative meniscus lens L32 having a convex surface facing the object anda biconvex lens L33 are cemented); the fourth lens group G4 is createdby disposing a cemented lens (in which a biconcave lens L41 and apositive meniscus lens L42 having the convex surfaces facing the objectare cemented); and the fifth lens group G5 is created by disposing abiconvex lens L51, a cemented lens (in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented), a cemented lens(in which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented), and a negative meniscuslens L57 having a concave surface facing the object. Each lens groupprepared like this is disposed according to the above mentionedprocedure, whereby the zooming optical system ZL is manufactured.

A seventh preferred embodiment of the present invention will now bedescribed with reference to the drawings. As shown in FIG. 1, a zoomingoptical system ZL according to the seventh preferred embodiment isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. In this zoomingoptical system ZL, it is preferable that the first lens group G1 ismoved toward the image plane I along the optical axis upon zooming. Bythis configuration, aberration fluctuation during zooming can bedecreased. Moreover, the refractive power of the first lens group G1 canbe weakened, hence a worsening of aberrations, when decentering isgenerated due to manufacturing error, can be controlled.

In the zooming optical system ZL, it is preferable that at least a partof the second lens group G2 to the fifth lens group G5 (a plurality oflens groups, one of the lens groups, or a part of the lensesconstituting any of the lens groups) is moved so as to include acomponent orthogonal to the optical axis. In this case, it is morepreferable that at least a part of the second lens group G2 is moved soas to include a component orthogonal to the optical axis. By thisconfiguration, camera shake can be corrected by a lens having a smalldiameter, therefore the size of the lens barrel can be smaller.

Conditions to construct the zooming optical system ZL according to theseventh preferred embodiment will now be described. It is preferablethat the zooming optical system ZL satisfies the following conditionalexpression (24).

4.41<f1/(−f2)<5.33  (24)

where f1 denotes a focal length of the first lens group G1, and f2denotes a focal length of the second lens group G2.

The conditional expression (24) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the secondlens group G2. By satisfying the conditional expression (24), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(24) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (24)is 4.45, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (24)is exceeded, the refractive power of the first lens group G1 decreasesand the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(24) is 5.30, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (25) is satisfied.

2.15<f1/f3<4.95  (25)

where f1 denotes a focal length of the first lens group G1, and f3denotes a focal length of the third lens group G3.

The conditional expression (25) specifies an appropriate focal length ofthe first lens group G1 with respect to the focal length of the thirdlens group G3. By satisfying the conditional expression (25), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(25) is not reached, the refractive power of the first lens group G1increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (25)is 2.20, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (25)is exceeded, the refractive power of the first lens group G1 decreases,and the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(25) is 4.35, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (26) is satisfied.

0.18<f3/(−f4)<0.92  (26)

where f3 denotes a focal length of the third lens group G3, and f4denotes a focal length of the fourth lens group G4.

The conditional expression (26) specifies an appropriate focal length ofthe third lens group G3 with respect to the focal length of the fourthlens group G4. By satisfying the conditional expression (26), sphericalaberration and chromatic aberration in the telephoto end state can becorrected well. If the lower limit value of the conditional expression(26) is not reached, the refractive power of the third lens group G3increases, and correction of spherical aberration and chromaticaberration in the telephoto end state becomes difficult, which is notdesirable. If the lower limit value of the conditional expression (26)is 0.22, the effect of the present application can be demonstrated withcertainty. If the upper limit value of the conditional expression (26)is exceeded, the refractive power of the third lens group G3 decreases,and the total length of the zooming optical system increases, which isnot desirable. If the upper limit value of the conditional expression(26) is 0.85, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that the followingconditional expression (27) is satisfied.

0.82<(−f4)/f5<1.58  (27)

where f4 denotes a focal length of the fourth lens group G4, and f5denotes a focal length of the fifth lens group G5.

The conditional expression (27) specifies an appropriate focal length ofthe fourth lens group G4 with respect to the focal length of the fifthlens group G5. By satisfying the conditional expression (27), curvatureof field and distortion in the wide-angle end state can be correctedwell. If the lower limit value of the conditional expression (27) is notreached, the refractive power of the fourth lens group G4 increases, andcorrection of chromatic aberration in the telephoto end state becomesdifficult, which is not desirable. If the lower limit value of theconditional expression (27) is 0.88, the effect of the presentapplication can be demonstrated with certainty. If the upper limit valueof the conditional expression (27) is exceeded, the refractive power ofthe fifth lens group G5 increases, and correction of curvature of fieldand distortion in the wide-angle end state becomes difficult, which isnot desirable. If the upper limit value of the conditional expression(27) is 1.52, the effect of the present application can be demonstratedwith certainty.

In the zooming optical system ZL, it is preferable that an aperture stopS is disposed in a position closer to the image than the second lensgroup G2. In this case, it is preferable that the aperture stop S isdisposed between the third lens group G3 and the fifth lens group G5. Itis more preferable that the aperture stop S is disposed between thethird lens group G3 and the fourth lens group G4. By this configuration,coma aberration and curvature of field can be corrected well.

In the zooming optical system ZL, it is preferable that at least a partof the third lens group G3 is moved along the optical axis uponfocusing. By this configuration, quick focusing is implemented, andfluctuation of angle of view and fluctuation of spherical aberrationduring focusing can be decreased.

In the zooming optical system ZL, it is preferable that the second lensgroup G2 is fixed with respect to the image plane I upon zooming. Bythis configuration, the lens barrel configuration during zooming can besimplified, and the size of the lens barrel can be smaller. Further,deterioration of optical performance, due to manufacturing error, can becontrolled.

In the zooming optical system ZL, it is preferable that all the lenssurfaces are spherical. By this configuration, processing, assembly andadjustment of the lenses become easier, and deterioration of opticalperformance, due to an error in processing, assembly and adjustment, canbe prevented. Even if the image plane is shifted, the drawingperformance is not affected very much, which is desirable.

In the zooming optical system ZL, an anti-reflection film, including atleast one layer formed by a wet process, is formed on at least onesurface of the optical surfaces of the n-th lens group Gn (fifth lensgroup G5 in this embodiment). The anti-reflection film formed in thezooming optical system ZL is a multilayer film, and the outermost layerof the multilayer film is preferably a layer formed by the wet process.By this configuration, the refractive index difference from air can bedecreased, hence reflection of the light can be decreased, and ghostsand flares can be further decreased.

In the zooming optical system ZL, the following conditional expression(28) is satisfied, where nd denotes a refractive index at d-line(wavelength: 587.6 nm) of the layer formed by the wet process. Bysatisfying this conditional expression, the refractive index differencefrom air can be decreased, hence reflection of light can be decreased,and ghosts and flares can be further decreased.

nd≤1.30  (28)

The anti-reflection film may include at least one layer of whichrefractive index is 1.30 or less, formed without using the wet process(using dry process or the like). By this configuration as well, the sameeffect as the case of using the wet process can be demonstrated. In thiscase, it is preferable that the layer of which refractive index is 1.30or less is the outermost layer out of the layers constituting themultilayer film.

As shown in FIG. 5, when the rays BM from the object side enter thezooming optical system ZL1, the rays are reflected on the object sidelens surface of the biconvex lens L55 (first ghost generation surface,corresponding to Surface Number 29), and the reflected rays arereflected again on the image side lens surface of the plano convex lensL54 (second ghost generation surface, corresponding to Surface Number28), reach the image plane I and generate a ghost. Although details willbe described later, the anti-reflection film according to each examplehas a multilayer structure (seven layers), the outermost layer (seventhlayer) is formed by the wet process, and the refractive index at d-lineis 1.26 (see Table 16 shown below).

An overview of the manufacturing method for the zooming optical systemZL according to the seventh embodiment will be described with referenceto FIG. 23. First the lens groups G1 to G5 are prepared by disposingeach lens (step S100). Each lens group is disposed so that the firstlens group G1 is moved along the optical axis upon zooming (step S200).Further, each lens group is disposed so that at least a part of thesecond lens group G2 to the fifth lens group G5 is moved so as toinclude a component orthogonal to the optical axis (step S300).Furthermore, each lens group is disposed so that each lens group G1 toG5 satisfies the above mentioned conditional expressions (24) and (25)(step S400).

In concrete terms, in the present embodiment as shown in FIG. 1 forexample, the first lens group G1 is created by disposing, in order fromthe object: a cemented lens (in which a negative meniscus lens L11having a convex surface facing the object and a biconvex lens L12 arecemented), and a positive meniscus lens L13 having a convex surfacefacing the object; the second lens group G2 is created by disposing acemented lens (in which a biconvex lens L21 and a biconcave lens L22 arecemented), a cemented lens (in which a biconcave lens L23 and a positivemeniscus lens L24 having a convex surface facing the object arecemented), and a biconcave lens L25; the third lens group G3 is createdby disposing a biconvex lens L31, and a cemented lens (in which anegative meniscus lens L32 having a convex surface facing the object anda biconvex lens L33 are cemented); the fourth lens group G4 is createdby disposing a cemented lens (in which a biconcave lens L41 and apositive meniscus lens L42 having the convex surfaces facing the objectare cemented); and the fifth lens group G5 is created by disposing abiconvex lens L51, a cemented lens (in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented), a cemented lens(in which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented), and a negative meniscuslens L57 having a concave surface facing the object. Each lens groupprepared like this is disposed according to the above mentionedprocedure, whereby the zooming optical system ZL is manufactured.

Now a camera, which is an optical apparatus that includes the zoomingoptical system ZL according to the embodiments, will be described withreference to FIG. 22. This camera 1 is a lens replaceable typemirrorless camera that includes the zooming optical system ZL accordingto the embodiments as an image capturing lens 2. In this camera 1, lightfrom an object (not illustrated) is collected by the image capturinglens 2, and forms an image of the object on the imaging plane of animaging unit 3 via OLPF (Optical Low-Pass Filter) (not illustrated). Theobject image is photo-electric converted by a photo-electric conversionelement disposed in the imaging unit 3, whereby an image of the objectis generated. This image is displayed on an EVF (Electronic View Finder)4 disposed on the camera 1. Thereby the user can view the object viaEVF4.

If the user presses a release button (not illustrated), thephoto-electric converted image by the imaging unit 3 is stored in memory(not illustrated). Thus the user can capture an image of the objectusing this camera 1. In the embodiments, an example of a mirrorlesscamera was described, but a similar effect as the case of the camera 1can be demonstrated even if the zooming optical system ZL, according tothe embodiments, is mounted in a camera main body of a single lensreflex type camera, which includes a quick return mirror, and views theobject by a finder optical system.

The following content can be adopted within a range where the opticalperformance is not diminished.

In the embodiments, the zooming optical system ZL constituted by fivelens groups or six lens groups was shown, but the conditions of theabove configuration or the like can be applied to a different number oflens groups, such as a seven lens group. A lens or a lens group may beadded to the side closest to the object, or a lens or a lens group maybe added to the side closest to the image. “Lens group” refers to aportion having at least one lens isolated by an air space which changesupon zooming.

A single lens group, a plurality of lens groups or a partial lens groupmay be designed as a focusing lens group, which performs focusing froman object at infinity to an object at a short distance by moving in theoptical axis direction. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for auto focusing(driving using an ultrasonic motor or the like). It is particularlypreferable that at least a part of the third lens group G3 is designedto be the focusing lens group, as mentioned above.

A lens group or a partial lens group may be designed to be avibration-isolating lens group, which corrects image blurs generated bycamera shake, by moving the lens group or the partial lens group in adirection to have a component orthogonal to the optical axis, or byrotating the lens group in an in-plane direction that includes theoptical axis. It is particularly preferable that at least a part of thesecond lens group G2 is designed to be the vibration-isolating lensgroup, as mentioned above.

The lens surface may be formed to be a spherical surface or a plane, oran aspherical surface. If the lens surface is a spherical surface or aplane, lens processing, assembly and adjustment are easy, as mentionedabove, and deterioration of optical performance, due to an error inprocessing, assembly and adjustment, can be prevented. Even if the imageplane is shifted, the drawing performance is not affected very much,which is desirable. If the lens surface is aspherical, the asphericalsurface can be any aspherical surface out of an aspherical surfacegenerated by grinding, a glass-molded aspherical surface generated byforming glass in an aspherical shape using a die, and a compositeaspherical surface generated by forming resin on the surface of theglass to be an aspherical shape. The lens surface may be a diffractionsurface, and the lens may be a refractive index-distributed lens (GRINlens) or a plastic lens.

It is preferable that the aperture stop S is disposed between the thirdlens group G3 and the fifth lens group G5, as mentioned above, but therole of the aperture stop may be substituted by the frame of the lens,without disposing a separate element as the aperture stop.

Each lens surface may be coated with an anti-reflection film which hashigh transmittance in a wide wavelength region in order to decreaseflares and ghosts, and implement a high optical performance with highcontrast.

The zoom ratio of the zooming optical system ZL of each embodiment isabout 3.0 to 7.0.

EXAMPLES

Each example of the present invention will now be described withreference to the drawings. FIG. 1, FIG. 6, FIG. 10, FIG. 14 and FIG. 18are cross-sectional views depicting the configuration of each zoomingoptical system ZL (ZL1 to ZL5) and the allocation of refractive poweraccording to each example. In the lower part of the cross-sectionalviews of the zooming optical systems ZL1 to ZL5, the moving direction ofeach lens group G1 to G5 or G6, upon zooming from a wide-angle end state(W) to a telephoto end state (T) along the optical axis, is shown by anarrow mark. In all the examples, the first lens group G1 moves along theoptical axis with respect to the image plane I upon zooming.

Example 1

FIG. 1 shows a configuration of a zooming optical system ZL1 accordingto Example 1. The zooming optical system ZL1 shown in FIG. 1 isconstituted by, in order from an object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. The first lensgroup G1 includes, in order from the object: a cemented lens in which anegative meniscus lens L11 having a convex surface facing the object anda biconvex lens L12 are cemented; and a positive meniscus lens L13having a convex surface facing the object. The second lens group G2includes, in order from the object: a cemented lens in which a biconvexlens L21 and a biconcave lens L22 are cemented; a cemented lens in whicha biconcave lens L23 and a positive meniscus lens L24 having a convexsurface facing the object are cemented; and a biconcave lens L25. Thethird lens group G3 includes, in order from the object: a biconvex lensL31; and a cemented lens in which a negative meniscus lens L32 having aconvex surface facing the object and a biconvex lens L33 are cemented.The fourth lens group G4 includes, in order from the object: a cementedlens in which a biconcave lens L41 and a positive meniscus lens L42having a convex surface facing the object are cemented in order from theobject. The fifth lens group G5 includes, in order from the object: abiconvex lens L51; a cemented lens in which a plano-convex lens L52having a convex surface facing the object, a plano-concave lens L53having a concave surface facing the image, and a plano-convex lens L54having a convex surface facing the object are cemented; a cemented lensin which a biconvex lens L55 and a plano-concave lens L56 having aconcave surface facing the object are cemented; and a negative meniscuslens L57 having a concave surface facing the object.

In the zooming optical system ZL1 according to Example 1, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1, the third lens group G3 and the fifth lens group G5 movetoward the object on the optical axis, and the second lens group G2 andthe fourth lens group G4 are fixed in the optical axis direction withrespect to the image plane I. The aperture stop S is disposed on theobject side of the fifth lens group G5, and moves with the fifth lensgroup G5 upon zooming.

Focusing from infinity to an object at a short distance is performed bymoving the third lens group G3 toward the image.

For image blur correction (vibration isolation), the cemented lens (inwhich the biconcave lens L23 and the positive meniscus lens L24 having aconvex surface facing the object are cemented) of the second lens groupG2 is designed to be a vibration-isolating lens group, and thisvibration-isolating lens group is moved so as to include a componentorthogonal to the optical axis. To correct a rotation blur of whichangle is θ using a lens of which focal length of the zooming opticalsystem is f and the vibration isolation coefficient (ratio of the imagemoving distance on the imaging surface with respect to the movingdistance of the vibration-isolating lens group VL in the image blurcorrection) is K, the vibration-isolating lens group for blur correctionis moved by (f·tan θ)/K in the direction orthogonal to the optical axis(this is the same for the other examples described below). In thewide-angle end state of Example 1, the vibration-isolation coefficientis −0.767 and focal length is 81.6 (mm), hence the moving distance ofthe vibration-isolating lens group for correcting a 0.2° rotation bluris −0.371 (mm). In the intermediate focal length state of Example 1, thevibration-isolation coefficient is −1.348 and focal length is 200.0(mm), hence the moving distance of the vibration-isolation lens groupfor correcting a 0.2° rotation blur is −0.518 (mm). In the telephoto endstate of Example 1, the vibration-isolation coefficient is −2.103 andfocal length is 392.0 (mm), hence the moving distance of thevibration-isolating lens group for correcting a 0.2° rotation blur is−0.651 (mm).

Table 1 shown below lists each data on Example 1. In [General Data] inTable 1, β is a zoom ratio, f is a focal length of the zooming opticalsystem, FNO is an F number, 2ω is an angle of view, Y is an imageheight, and TL is a total length. The total length TL here indicates adistance from surface 1 of the lens surface to the image plane I on theoptical axis in the infinity focusing state. In [Lens Data], m in thefirst column is the sequence of the lens surface counted from the objectin the light traveling direction (surface number), r in the secondcolumn is a radius of curvature of each lens surface, d in the thirdcolumn is a distance from each optical surface to the next opticalsurface on the optical axis (surface distance), vd in the fourth columnand nd in the fifth column are an Abbe number and a refractive index atd-line (λ=587.6 nm) respectively. The radius of curvature 0.000indicates a plane, and the refractive index of air 1.00000 is omitted.The surface numbers 1 to 33 in Table 1 correspond to the numbers 1 to 33in FIG. 1. [Focal Length of Lens Group] shows the first surface andfocal length of the first to fifth lens groups G1 to G5 respectively. Inall data values, “mm” is normally used as the unit of focal length f,radius of curvature r, surface distance d and other lengths, but theunit is not limited to “mm”, since an equivalent optical performance isacquired even if the optical system is proportionally expanded orproportionally reduced. Description on the symbols and description onthe data tables are the same for the other later mentioned examples.

TABLE 1 [General Data] β = 4.8 Intermediate Wide-angle focal lengthTelephoto end state state end state f = 81.6~ 200.0~ 392.0 ENO = 4.56~5.38~ 5.85 2ω = 29.6~ 12.1~ 6.2 Y = 21.6~ 21.6~ 21.6 TL = 246.4~ 283.4~302.5 [Lens Data] m r d νd nd 1 182.816 2.500 35.7 1.90265 2 92.56610.000  82.6 1.49782 3 −707.416 0.100 4 83.365 9.200 95.0 1.43700 51420.361 D1 6 117.082 6.400 34.9 1.80100 7 −117.044 2.200 82.6 1.49782 861.183 5.810 9 −265.081 2.000 46.6 1.81600 10 30.785 4.600 25.5 1.8051811 92.264 6.200 12 −56.342 2.000 42.7 1.83481 13 158.965 D2 14 112.2524.600 67.9 1.59319 15 −78.685 0.100 16 67.612 1.800 31.3 1.90366 1735.499 6.400 67.9 1.59319 18 −238.177 D3 19 −58.467 1.600 54.6 1.7291620 38.999 3.600 35.7 1.90265 21 146.900 D4 22 0.000 2.000 Aperture stopS 23 124.142 3.400 44.8 1.74400 24 −124.142 0.100 25 26.615 6.800 70.31.48749 26 0.000 2.000 29.4 1.95000 27 26.437 4.800 52.2 1.51742 280.000 17.600  29 176.178 6.000 33.7 1.64769 30 −19.703 1.600 65.41.60300 31 0.000 11.270  32 −22.131 1.600 42.7 1.83481 33 −33.748 BF[Focal Length of Lens Group] Lens group First surface Focal length Firstlens group 1 161.714 Second lens group 6 −32.531 Third lens group 1450.816 Fourth lens group 19 −70.030 Fifth lens group 23 59.673

In Example 1, the axial air distance D1 between the first lens group G1and the second lens group G2, the axial air distance D2 between thesecond lens group G2 and the third lens group G3, the axial air distanceD3 between the third lens group G3 and the fourth lens group G4, theaxial air distance D4 between the fourth lens group G4 and the aperturestop S which moves together with the fifth lens group G5, and the backfocus BF change upon zooming. Table 2 shows the values of the variabledistances D1 to D4 and the back focus BF at each focal length in thewide-angle end state, the intermediate focal length state and thetelephoto end state upon focusing on infinity. The back focus BFindicates a distance from the lens surface closest to the image (Surface33 in FIG. 1) to the image plane I on the optical axis. This descriptionis the same for the other later mentioned examples.

TABLE 2 [Variable Distance Data] Intermediate Wide-angle focal lengthTelephoto end state state end state f 81.6~ 200.0~ 392.0 D1 8.225~45.191~ 64.292 D2 27.059~ 15.341~ 3.056 D3 5.388~ 17.106~ 29.391 D426.684~ 11.153~ 2.382 BF 52.8~ 68.3~ 77.1

Table 3 shows values corresponding to each conditional expression inExample 1. In Table 3, f1 is a focal length of the first lens group G1,f2 is a focal length of the second lens group G2, f4 is a focal lengthof the fourth lens group G4, and f5 is a focal length of the fifth lensgroup G5. Description of the symbols is the same for the other latermentioned examples.

TABLE 3  (1) f1/(−f2) = 4.97  (2) f1/f3 = 3.18  (3) f3/(−f4) = 0.73  (4)(−f4)/f5 = 1.17  (5) f1/(−f2) = 4.97  (6) f3/f5 = 0.85  (7) f1/(−f4) =2.31  (8) f2/f4 = 0.46  (9) ft/(−f2) = 12.1 (10) ft/(−f4) = 5.6 (11)(−f4)/f5 = 1.2 (12) (−f2)/f5 = 0.6 (13) f1/(−f2) = 5.0 (14) f1/(−f4) =2.3 (15) f1/f5 = 2.7 (16) (−f4)/f5 = 1.2 (17) (−f2)/f5 = 0.6 (18)f1/(−f2) = 4.97 (19) (−f4)/f5 = 1.17 (20) f1/(−f4) = 2.31 (21) (−f2)/f3= 0.64 (22) (−f4)/f5 = 1.17 (23) f3/(−f4) = 0.73 (24) f1/(−f2) = 4.97(25) f1/f3 = 3.18 (26) f3/(−f4) = 0.73 (27) (−f4)/f5 = 1.17

As a result, the zooming optical system ZL1 of Example 1 satisfies allthe conditional expressions (1) to (27).

FIG. 2A is a set of graphs showing various aberrations of Example 1 uponfocusing on infinity in the wide-angle end state, FIG. 3A is a set ofgraphs showing various aberrations of Example 1 upon focusing oninfinity in the intermediate focal length state, and FIG. 4A is a set ofgraphs showing various aberrations of Example 1 upon focusing oninfinity in the telephoto end state. FIG. 2B is a set of graphs showingcoma aberration of Example 1 when image blur is corrected upon focusingon infinity in the wide-angle end state (shift amount ofvibration-isolating lens group=−0.371), FIG. 3B is a set of graphsshowing coma aberration of Example 1 when image blur is corrected uponfocusing on infinity in the intermediate focal length state (shiftamount of vibration-isolating lens group=−0.518), and FIG. 4B is a setof graphs showing coma aberration of Example 1 when image blur iscorrected upon focusing on infinity in the telephoto end state (shiftamount of vibration-isolating lens group=−0.651). In each graph showingaberrations, FNO is an F number, A is a half-angle of view, d is anindividual aberration at d-line (λ=587.6 nm), and g is an individualaberration at g-line (λ=435.6 nm). The solid line in each graph showingastigmatism indicates the sagittal image surface, and the broken lineindicates the meridional image surface. The description on the graphsshowing aberrations is the same for the other later mentioned examples.As each graph showing aberrations clarifies, in Example 1, the zoomingoptical system has an excellent image forming performance, where variousaberrations are corrected well in each focal length state from thewide-angle end state to the telephoto end state.

FIG. 5 is the zooming optical system according to Example 1, depictingan example of a state of the incident rays reflecting on the first ghostgeneration surface and the second ghost generation surface, generatingghosts and flares on the image plane I.

Example 2

FIG. 6 shows a configuration of a zooming optical system ZL2 accordingto Example 2. The zooming optical system ZL2 shown in FIG. 6 isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; a fifthlens group G5 having positive refractive power; and a sixth lens groupG6 having negative refractive power. The first lens group G1 includes,in order from the object: a cemented lens in which a negative meniscuslens L11 having a convex surface facing the object and a biconvex lensL12 are cemented; and a biconvex lens L13. The second lens group G2includes, in order from the object: a cemented lens in which a positivemeniscus lens L21 having a concave surface facing the object and abiconcave lens L22 are cemented; a cemented lens in which a biconcavelens L23 and a positive meniscus lens L24 having a convex surface facingthe object are cemented; and a biconcave lens L25. The third lens groupG3 includes, in order from the object: a biconvex lens L31; and acemented lens in which a biconvex lens L32 and a negative meniscus lensL33 having a concave surface facing the object are cemented. The fourthlens group G4 includes a cemented lens in which a biconcave lens L41 anda biconvex lens L42 are cemented in order from the object. The fifthlens group G5 includes, in order from the object: a biconvex lens L51;and a cemented lens in which a biconvex lens L52 and a negative meniscuslens L53 having a concave surface facing the object are cemented. Thesixth lens group G6 includes a cemented lens in which a biconvex lensL61 and a biconcave lens L62 are cemented in order from the object.

In the zooming optical system ZL2 according to Example 2, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1, the third lens group G3, the fifth lens group G5 and the sixthlens group G6 move toward the object on the optical axis, and the secondlens group G2 and the fourth lens group G4 are fixed in the optical axisdirection with respect to the image plane I. The aperture stop S isdisposed on the object side of the fifth lens group G5, and moves withthe fifth lens group G5 upon zooming.

Focusing from infinity to an object at a short distance is performed bymoving the third lens group G3 toward the image.

For image blur correction (vibration isolation), the cemented lens (inwhich the biconcave lens L23 and the positive meniscus lens L24 having aconvex surface facing the object are cemented) of the second lens groupG2 is designed to be a vibration-isolating lens group, and thisvibration-isolating lens group is moved so as to include a componentorthogonal to the optical axis. In the wide-angle end state of Example2, the vibration-isolation coefficient is −0.637 and focal length is72.0 (mm), hence the moving distance of the vibration-isolating lensgroup for correcting a 0.2° rotation blur is −0.395 (mm). In theintermediate focal length state of Example 2, the vibration-isolationcoefficient is −1.158 and focal length is 200.0 (mm), hence the movingdistance of the vibration-isolation lens group for correcting a 0.2°rotation blur is −0.603 (mm). In the telephoto end state of Example 2,the vibration-isolation coefficient is −1.763 and focal length is 390.0(mm), hence the moving distance of the vibration-isolating lens groupfor correcting a 0.2° rotation blur is −0.772 (mm).

Table 4 shown below lists each data on Example 2. The surface numbers 1to 30 in Table 4 correspond to numbers 1 to 30 in FIG. 6. [Focal Lengthof Lens Group] shows the first surface and the focal length of the firstto sixth lens groups G1 to G6 respectively.

TABLE 4 [General Data] β = 5.4 Intermediate Wide-angle focal lengthTelephoto end state state end state f = 72.0~ 200.0~ 390.0 ENO = 4.54~5.44~ 5.88 2ω = 33.7~ 12.0~ 6.2 Y = 21.6~ 21.6~ 21.6 TL = 244.3~ 290.3~309.3 [Lens Data] m r d νd nd 1 218.093 1.800 40.7 1.88300 2 94.34110.098  82.6 1.49782 3 −579.376 0.100 4 90.320 9.392 82.6 1.49782 5−1839.350 D1 6 −1407.394 4.344 25.5 1.80518 7 −80.390 2.000 67.9 1.593198 128.565 4.528 9 −287.557 1.900 42.7 1.83481 10 40.640 3.951 23.81.84666 11 116.253 5.759 12 −69.042 1.800 42.7 1.83481 13 177.936 D2 14102.836 4.827 60.2 1.64000 15 −70.986 0.100 16 85.954 5.583 61.2 1.5891317 −58.889 2.000 23.8 1.84666 18 −910.681 D3 19 −57.570 1.800 47.41.78800 20 50.018 3.583 23.8 1.84666 21 −2308.874 D4 22 0.000 2.000Aperture stop S 23 1105.472 3.337 50.3 1.71999 24 −60.251 0.100 2553.693 5.265 70.3 1.48749 26 −61.018 2.000 23.8 1.84666 27 −839.528 D528 43.363 5.139 28.4 1.72825 29 −106.243 1.500 40.7 1.88300 30 33.800 BF[Focal Length of Lens Group] Lens group First surface Focal length Firstlens group 1 151.809 Second lens group 6 −32.015 Third lens group 1453.583 Fourth lens group 19 −82.521 Fifth lens group 23 58.368 Sixthlens group 28 −110.027

In Example 2, the axial air distance D1 between the first lens group G1and the second lens group G2, the axial air distance D2 between thesecond lens group G2 and the third lens group G3, the axial air distanceD3 between the third lens group G3 and the fourth lens group G4, theaxial air distance D4 between the fourth lens group G4 and the aperturestop S which moves together with the fifth lens group G5, the axial airdistance D5 between the fifth lens group G5 and the sixth lens group G6and the back focus BF change upon zooming. Table 5 shows the values ofthe variable distances D1 to D5 and the back focus BF at each focallength in the wide-angle end state, the intermediate focal length stateand the telephoto end state upon focusing on infinity.

TABLE 5 [Variable Distance Data] Intermediate Wide-angle focal lengthTelephoto end state state end state f 72.0~ 200.0~ 390.0 D1 2.000~47.946~ 67.000 D2 28.700~ 17.520~ 3.000 D3 15.940~ 29.759~ 42.880 D429.040~ 8.875~ 2.000 D5 30.005~ 22.265~ 23.642 BF 55.7~ 81.0~ 87.9

Table 6 shows a value corresponding to each conditional expressionaccording to Example 2.

TABLE 6  (1) f1/(−f2) = 4.74  (2) f1/f3 = 2.83  (3) f3/(−f4) = 0.65  (4)(−f4)/f5 = 1.41  (5) f1/(−f2) = 4.74  (6) f3/f5 = 0.92  (7) f1/(−f4) =1.84  (8) f2/f4 = 0.39  (9) ft/(−f2) = 12.2 (10) ft/(−f4) = 4.7 (11)(−f4)/f5 = 1.4 (12) (−f2)/f5 = 0.6 (13) f1/(−f2) = 4.7 (14) f1/(−f4) =1.8 (15) f1/f5 = 2.6 (16) (−f4)/f5 = 1.4 (17) (−f2)/f5 = 0.6 (18)f1/(−f2) = 4.74 (19) (−f4)/f5 = 1.41 (20) f1/(−f4) = 1.84 (21) (−f2)/f3= 0.60 (22) (−f4)/f5 = 1.41 (23) f3/(−f4) = 0.65 (24) f1/(−f2) = 4.74(25) f1/f3 = 2.83 (26) f3/(−f4) = 0.65 (27) (−f4)/f5 = 1.41

As a result, the zooming optical system ZL2 of Example 2 satisfies allthe conditional expressions (1) to (27).

FIG. 7A is a set of graphs showing various aberrations of Example 2 uponfocusing on infinity in the wide-angle end state, FIG. 8A is a set ofgraphs showing various aberrations of Example 2 upon focusing oninfinity in the intermediate focal length state, and FIG. 9A is a set ofgraphs showing various aberrations of Example 2 upon focusing oninfinity in the telephoto end state. FIG. 7B is a set of graphs showingcoma aberration of Example 2 when image blur is corrected upon focusingon infinity in the wide-angle end state (shift amount ofvibration-isolating lens group=−0.395), FIG. 8B is a set of graphsshowing coma aberration of Example 2 when image blur is corrected uponfocusing on infinity in the intermediate focal length state (shiftamount of vibration-isolating lens group=−0.603), and FIG. 9B is a setof graphs showing coma aberration of Example 2 when image blur iscorrected upon focusing on infinity in the telephoto end state (shiftamount of vibration-isolating lens group=−0.772). As each graph showingaberrations clarifies, in Example 2, the zooming optical system has anexcellent image forming performance, where various aberrations arecorrected well in each focal length state from the wide-angle end stateto the telephoto end state.

Example 3

FIG. 10 shows a configuration of a zooming optical system ZL3 accordingto Example 3. The zooming optical system ZL3 shown in FIG. 10 isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; a fifthlens group G5 having positive refractive power; and a sixth lens groupG6 having negative refractive power. The first lens group G1 includes,in order from the object: a cemented lens in which a negative meniscuslens L11 having a convex surface facing the object and a biconvex lensL12 are cemented; and a biconvex lens L13. The second lens group G2includes, in order from the object: a cemented lens in which a biconvexlens L21 and a biconcave lens L22 are cemented; a cemented lens in whicha positive meniscus lens L23 having a concave surface facing the objectand a biconcave lens L24 are cemented; and a biconcave lens L25. Thethird lens group G3 includes, in order from the object: a biconvex lensL31; and a cemented lens in which a biconvex lens L32 and a biconcavelens L33 are cemented. The fourth lens group G4 includes a cemented lensin which a biconcave lens L41 and a positive meniscus lens L42 having aconvex surface facing the object are cemented in order from the object.The fifth lens group G5 includes, in order from the object: a cementedlens in which a negative meniscus lens L51 having a convex surfacefacing the object and a biconvex lens L52 are cemented; and a cementedlens in which a biconvex lens L53 and a negative meniscus lens L54having a concave surface facing the object are cemented. The sixth lensgroup G6 includes a cemented lens in which a biconvex lens L61 and abiconcave lens L62 are cemented in order from the object.

In the zooming optical system ZL3 according to Example 3, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1, the third lens group G3 and the fifth lens group G5 and thesixth lens group G6 move toward the object on the optical axis, and thesecond lens group G2 and the fourth lens group G4 are fixed in theoptical axis direction with respect to the image plane I. The aperturestop S is disposed on the object side of the fifth lens group G5, andmoves with the fifth lens group G5 upon zooming.

Focusing from infinity to an object at a short distance is performed bymoving the third lens group G3 toward the image.

For image blur correction (vibration isolation), the entire second lensgroup G2 is designed to be a vibration-isolating lens group, and thisvibration-isolating lens group is moved so as to include a componentorthogonal to the optical axis. In the wide-angle end state of Example3, the vibration-isolation coefficient is −1.972 and focal length is72.0 (mm), hence the moving distance of the vibration-isolating lensgroup for correcting a 0.2° rotation blur is −0.127 (mm). In theintermediate focal length state of Example 3, the vibration-isolationcoefficient is −3.534 and focal length is 200.0 (mm), hence the movingdistance of the vibration-isolation lens group for correcting a 0.2°rotation blur is −0.198 (mm). In the telephoto end state of Example 3,the vibration-isolation coefficient is −5.379 and focal length is 390.0(mm), hence the moving distance of the vibration-isolating lens groupfor correcting a 0.2° rotation blur is −0.253 (mm).

Table 7 shown below lists each data on Example 3. The surface numbers 1to 31 in Table 7 correspond to numbers 1 to 31 in FIG. 10. [Focal Lengthof Lens Group] shows the first surface and the focal length of the firstto sixth lens groups G1 to G6 respectively.

TABLE 7 [General Data] β = 5.4 Intermediate Wide-angle focal lengthTelephoto end state state end state f = 72.0~ 200.0~ 390.0 ENO = 4.52~5.34~ 5.78 2ω = 34.0~ 12.1~ 6.2 Y = 21.6~ 21.6~ 21.6 TL = 239.3~ 285.8~304.3 [Lens Data] m r d νd nd 1 235.129 2.000 40.7 1.88300 2 85.93710.435  82.6 1.49782 3 −492.987 0.100 4 81.734 9.789 82.6 1.49782 5−2477.191 D1 6 94.480 3.279 28.7 1.79504 7 −1045.056 2.000 67.9 1.593198 57.468 3.373 9 −137.861 3.251 28.7 1.79504 10 −48.070 2.000 67.91.59319 11 69.776 3.889 12 −56.313 1.800 49.6 1.77250 13 135.256 D2 14220.803 5.100 67.9 1.59319 15 −51.295 0.100 16 48.045 5.380 67.9 1.5931917 −156.768 2.000 31.3 1.90366 18 209.257 D3 19 −51.770 1.500 54.61.72916 20 41.489 3.613 34.9 1.80100 21 331.492 D4 22 0.000 2.000Aperture stop S 23 86.564 2.000 40.7 1.88300 24 47.702 5.771 52.21.51742 25 −52.610 0.100 26 60.874 4.753 82.6 1.49782 27 −65.980 2.00023.8 1.84666 28 −423.943 D5 29 43.795 3.743 27.6 1.75520 30 −80.6301.500 40.7 1.88300 31 36.787 BF [Focal Length of Lens Group] Lens groupFirst surface Focal length First lens group 1 151.723 Second lens group6 −31.512 Third lens group 14 48.052 Fourth lens group 19 −67.397 Fifthlens group 23 58.111 Sixth lens group 29 −140.788

In Example 3, the axial air distance D1 between the first lens group G1and the second lens group G2, the axial air distance D2 between thesecond lens group G2 and the third lens group G3, the axial air distanceD3 between the third lens group G3 and the fourth lens group G4, theaxial air distance D4 between the fourth lens group G4 and the aperturestop S which moves together with the fifth lens group G5, the axial airdistance D5 between the fifth lens group G5 and the sixth lens group G6and the back focus BF change upon zooming. Table 8 shows the values ofthe variable distances D1 to D5 and the back focus BF at each focallength in the wide-angle end state, the intermediate focal length stateand the telephoto end state upon focusing on infinity.

TABLE 8 [Variable Distance Data] Intermediate Wide-angle focal lengthTelephoto end state state end state f 72.0~ 200.0~ 390.0 D1 2.000~48.459~ 67.000 D2 25.107~ 13.069~ 2.000 D3 6.466~ 18.504~ 29.573 D429.312~ 12.120~ 2.428 D5 32.947~ 32.202~ 30.353 BF 55.1~ 73.0~ 84.5

Table 9 shows a value corresponding to each conditional expressionaccording to Example 3.

TABLE 9  (1) f1/(−f2) = 4.81  (2) f1/f3 = 3.16  (3) f3/(−f4) = 0.71  (4)(−f4)/f5 = 1.16  (5) f1/(−f2) = 4.81  (6) f3/f5 = 0.83  (7) f1/(−f4) =2.25  (8) f2/f4 = 0.47  (9) ft/(−f2) = 12.4 (10) ft/(−f4) = 5.8 (11)(−f4)/f5 = 1.2 (12) (−f2)/f5 = 0.5 (13) f1/(−f2) = 4.8 (14) f1/(−f4) =2.3 (15) f1/f5 = 2.6 (16) (−f4)/f5 = 1.2 (17) (−f2)/f5 = 0.5 (18)f1/(−f2) = 4.81 (19) (−f4)/f5 = 1.16 (20) f1/(−f4) = 2.25 (21) (−f2)/f3= 0.66 (22) (−f4)/f5 = 1.16 (23) f3/(−f4) = 0.71 (24) f1/(−f2) = 4.81(25) f1/f3 = 3.16 (26) f3/(−f4) = 0.71 (27) (−f4)/f5 = 1.16

As a result, the zooming optical system ZL3 of Example 3 satisfies allthe conditional expressions (1) to (27).

FIG. 11A is a set of graphs showing various aberrations of Example 3upon focusing on infinity in the wide-angle end state, FIG. 12A is a setof graphs showing various aberrations of Example 3 upon focusing oninfinity in the intermediate focal length state, and FIG. 13A is a setof graphs showing various aberrations of Example 3 upon focusing oninfinity in the telephoto end state. FIG. 11B is a set of graphs showingcoma aberration of Example 3 when image blur is corrected upon focusingon infinity in the wide-angle end state (shift amount ofvibration-isolating lens group=−0.127), FIG. 12B is a set of graphsshowing coma aberration of Example 3 when image blur is corrected uponfocusing on infinity in the intermediate focal length state (shiftamount of vibration-isolating lens group=−0.198), and FIG. 13B is a setof graphs showing coma aberration of Example 3 when image blur iscorrected upon focusing on infinity in the telephoto end state (shiftamount of vibration-isolating lens group=−0.253). As each graph showingaberrations clarifies, in Example 3, the zooming optical system has anexcellent image forming performance, where various aberrations arecorrected well in each focal length state from the wide-angle end stateto the telephoto end state.

Example 4

FIG. 14 shows a configuration of a zooming optical system ZL4 accordingto Example 4. The zooming optical system ZL4 shown in FIG. 14 isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; a fifthlens group G5 having positive refractive power; and a sixth lens groupG6 having negative refractive power. The first lens group G1 includes,in order from the object: a cemented lens in which a negative meniscuslens L11 having a convex surface facing the object and a biconvex lensL12 are cemented; and a biconvex lens L13. The second lens group G2includes, in order from the object: a cemented lens in which a biconvexlens L21 and a biconcave lens L22 are cemented; a cemented lens in whicha biconcave lens L23 and a positive meniscus lens L24 having a convexsurface facing the object are cemented; and a biconcave lens L25. Thethird lens group G3 includes, in order from the object: a biconvex lensL31; and a cemented lens in which a negative meniscus lens L32 having aconvex surface facing the object and a biconvex lens L33 are cemented.The fourth lens group G4 includes a cemented lens in which a biconcavelens L41 and a positive meniscus lens L42 having a convex surface facingthe object are cemented in order from the object. The fifth lens groupG5 includes, in order from the object: a cemented lens in which anegative meniscus lens L51 having a convex surface facing the object anda biconvex lens L52 are cemented; and a cemented lens in which abiconvex lens L53 and a negative meniscus lens L54 having a concavesurface facing the object are cemented. The sixth lens group G6 includesa cemented lens in which a biconvex lens L61 and a biconcave lens L62are cemented in order from the object.

In the zooming optical system ZL4 according to Example 4, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1, the third lens group G3, the fifth lens group G5 and the sixthlens group G6 move toward the object on the optical axis, and the secondlens group G2 and the fourth lens group G4 are fixed in the optical axisdirection with respect to the image plane I. The aperture stop S isdisposed on the object side of the fifth lens group G5, and moves withthe fifth lens group G5 upon zooming.

Focusing from infinity to an object at a short distance is performed bymoving the third lens group G3 toward the image.

For image blur correction (vibration isolation), the cemented lens (inwhich the biconcave lens L23 and the positive meniscus lens L24 having aconvex surface facing the object are cemented) of the second lens groupG2 is designed to be a vibration-isolating lens group, and thisvibration-isolating lens group is moved so as to include a componentorthogonal to the optical axis. In the wide-angle end state of Example4, the vibration-isolation coefficient is −0.888 and focal length is82.0 (mm), hence the moving distance of the vibration-isolating lensgroup for correcting a 0.2° rotation blur is −0.322 (mm). In theintermediate focal length state of Example 4, the vibration-isolationcoefficient is −1.454 and focal length is 200.0 (mm), hence the movingdistance of the vibration-isolation lens group for correcting a 0.2°rotation blur is −0.480 (mm). In the telephoto end state of Example 4,the vibration-isolation coefficient is −2.176 and focal length is 390.0(mm), hence the moving distance of the vibration-isolating lens groupfor correcting a 0.2° rotation blur is −0.626 (mm).

Table 10 shown below lists each data on Example 4. The surface numbers 1to 31 in Table 10 correspond to numbers 1 to 31 in FIG. 14. [FocalLength of Lens Group] shows the first surface and the focal length ofthe first to sixth lens groups G1 to G6 respectively.

TABLE 10 [General Data] β = 4.8 Intermediate Wide-angle focal lengthTelephoto end state state end state f = 82.0~ 200.0~ 390.0 ENO = 5.05~5.61~ 5.82 2ω = 29.7~ 12.0~ 6.2 Y = 21.6~ 21.6~ 21.6 TL = 241.3~ 283.3~303.3 [Lens Data] m r d νd nd 1 227.795 2.000 40.7 1.88300 2 84.74710.413  82.6 1.49782 3 −538.594 0.100 4 82.998 9.958 82.6 1.49782 5−1048.042 D1 6 170.969 6.158 34.9 1.80100 7 −66.891 2.000 65.4 1.60300 882.527 5.163 9 −168.234 2.000 47.4 1.78800 10 41.763 3.001 23.8 1.8466611 88.369 6.493 12 −43.051 1.800 46.6 1.81600 13 411.913 D2 14 137.0434.617 63.3 1.61800 15 −72.111 0.100 16 62.009 2.000 31.3 1.90366 1734.150 6.473 63.3 1.61800 18 −167.969 D3 19 −50.276 1.500 50.3 1.7199920 34.293 4.000 28.7 1.79504 21 221.433 D4 22 0.000 2.000 Aperture stopS 23 178.755 2.000 23.8 1.84666 24 75.314 5.063 63.9 1.51680 25 −50.1460.107 26 72.928 4.620 58.8 1.51823 27 −62.568 2.000 23.8 1.84666 28−197.918 D5 29 42.990 4.937 29.6 1.71736 30 −55.338 1.500 42.7 1.8348131 37.334 BF [Focal Length of Lens Group] Lens group First surface Focallength First lens group 1 148.584 Second lens group 6 −29.113 Third lensgroup 14 44.313 Fourth lens group 19 −63.143 Fifth lens group 23 59.877Sixth lens group 29 −157.384

In Example 4, the axial air distance D1 between the first lens group G1and the second lens group G2, the axial air distance D2 between thesecond lens group G2 and the third lens group G3, the axial air distanceD3 between the third lens group G3 and the fourth lens group G4, theaxial air distance D4 between the fourth lens group G4 and the aperturestop S which moves together with the fifth lens group G5, the axial airdistance D5 between the fifth lens group G5 and the sixth lens group G6and the back focus BF change upon zooming. Table 11 shows the values ofthe variable distances D1 to D5 and the back focus BF at each focallength in the wide-angle end state, the intermediate focal length stateand the telephoto end state upon focusing on infinity.

TABLE 11 [Variable Distance Data] Intermediate Wide-angle focal lengthTelephoto end state state end state f 82.0~ 200.0 390.0 D1 2.299~ 44.30564.299 D2 24.152~ 13.739 2.000 D3 7.126~ 17.538 29.278 D4 17.672~ 6.7132.399 D5 32.546~ 31.055 23.798 BF 58.1~ 70.5 82.1

Table 12 shows a value corresponding to each conditional expressionaccording to Example 4.

TABLE 12  (1) f1/(−f2) = 5.10  (2) f1/f3 = 3.35  (3) f3/(−f4) = 0.70 (4) (−f4)/f5 = 1.05  (5) f1/(−f2) = 5.10  (6) f3/f5 = 0.74  (7)f1/(−f4) = 2.35  (8) f2/f4 = 0.46  (9) ft/(−f2) = 13.4 (10) ft/(−f4) =6.2 (11) (−f4)/f5 = 1.1 (12) (−f2)/f5 = 0.5 (13) f1/(−f2) = 5.1 (14)f1/(−f4) = 2.4 (15) f1/f5 = 2.5 (16) (−f4)/f5 = 1.1 (17) (−f2)/f5 = 0.5(18) f1/(−f2) = 5.10 (19) (−f4)/f5 = 1.05 (20) f1/(−f4) = 2.35 (21)(−f2)/f3 = 0.66 (22) (−f4)/f5 = 1.05 (23) f3/(−f4) = 0.70 (24) f1/(−f2)= 5.10 (25) f1/f3 = 3.35 (26) f3/(−f4) = 0.70 (27) (−f4)/f5 = 1.05

As a result, the zooming optical system ZL4 of Example 4 satisfies allthe conditional expressions (1) to (27).

FIG. 15A is a set of graphs showing various aberrations of Example 4upon focusing on infinity in the wide-angle end state, FIG. 16A is a setof graphs showing various aberrations of Example 4 upon focusing oninfinity in the intermediate focal length state, and FIG. 17A is a setof graphs showing various aberrations of Example 4 upon focusing oninfinity in the telephoto end state. FIG. 15B is a set of graphs showingcoma aberration of Example 3 when image blur is corrected upon focusingon infinity in the wide-angle end state (shift amount ofvibration-isolating lens group=−0.322), FIG. 16B is a set of graphsshowing coma aberration when image blur is corrected upon focusing oninfinity in the intermediate focal length state (shift amount ofvibration-isolating lens group=−0.480), and FIG. 17B is a set of graphsshowing coma aberration when image blur is corrected upon focusing oninfinity in the telephoto end state (shift amount of vibration-isolatinglens group=−0.626). As each graph showing aberrations clarifies, inExample 4, the zooming optical system has an excellent image formingperformance, where various aberrations are corrected well in each focallength state from the wide-angle end state to the telephoto end state.

Example 5

FIG. 18 shows a configuration of a zooming optical system ZL5 accordingto Example 5. The zooming optical system ZL5 shown in FIG. 18 isconstituted by, in order from the object: a first lens group G1 havingpositive refractive power; a second lens group G2 having negativerefractive power; a third lens group G3 having positive refractivepower; a fourth lens group G4 having negative refractive power; and afifth lens group G5 having positive refractive power. The first lensgroup G1 includes, in order from the object: a cemented lens in which anegative meniscus lens L11 having a convex surface facing the object anda biconvex lens L12 are cemented; and a positive meniscus lens L13having a convex surface facing the object. The second lens group G2includes, in order from the object: a cemented lens in which a biconvexlens L21 and a biconcave lens L22 are cemented; a cemented lens in whicha biconcave lens L23 and a positive meniscus lens L24 having a convexsurface facing the object are cemented; and a biconcave lens L25. Thethird lens group G3 includes, in order from the object: a biconvex lensL31; and a cemented lens in which a negative meniscus lens L32 having aconvex surface facing the object and a biconvex lens L33 are cemented.The fourth lens group G4 includes a cemented lens in which a biconcavelens L41 and a biconvex lens L42 are cemented in order from the object.The fifth lens group G5 includes, in order from the object: a biconvexlens L51, a cemented lens in which a negative meniscus lens L52 having aconvex surface facing the object and a positive meniscus lens L53 havinga convex surface facing the object are cemented; and a cemented lens inwhich a biconvex lens L54 and a biconcave lens L55 are cemented.

In the zooming optical system ZL5 according to Example 5, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1, the third lens group G3, the fourth lens group G4 and thefifth lens group G5 move toward the object on the optical axis, and thesecond lens group G2 is fixed in the optical axis direction with respectto the image plane I. The aperture stop S is disposed on the object sideof the fourth lens group G4, and moves with the fourth lens group G4upon zooming.

Focusing from infinity to an object at a short distance is performed bymoving the third lens group G3 toward the image.

For image blur correction (vibration isolation), the cemented lens (inwhich the biconcave lens L23 and the positive meniscus lens L24 having aconvex surface facing the object are cemented) of the second lens groupG2 is designed to be a vibration-isolating lens group, and thisvibration-isolating lens group is moved so as to include a componentorthogonal to the optical axis. In the wide-angle end state of Example5, the vibration-isolation coefficient is −0.858 and focal length is103.0 (mm), hence the moving distance of the vibration-isolating lensgroup for correcting a 0.2° rotation blur is −0.419 (mm). In theintermediate focal length state of Example 4, the vibration-isolationcoefficient is −1.297 and focal length is 200.0 (mm), hence the movingdistance of the vibration-isolation lens group for correcting a 0.2°rotation blur is −0.538 (mm). In the telephoto end state of Example 4,the vibration-isolation coefficient is −1.987 and focal length is 388.0(mm), hence the moving distance of the vibration-isolating lens groupfor correcting a 0.2° rotation blur is −0.682 (mm).

Table 13 shown below lists each data on Example 5. The surface numbers 1to 30 in Table 13 correspond to numbers 1 to 30 in FIG. 18. [FocalLength of Lens Group] shows the first surface and the focal length ofthe first to fifth lens groups G1 to G5 respectively.

TABLE 13 [General Data] β = 3.8 Intermediate Wide-angle focal lengthTelephoto end state state end state f = 103.0~ 200.0~ 388.0 ENO = 4.84~5.30~ 5.86 2ω = 23.4~ 12.0~ 6.2 Y = 21.6~ 21.6~ 21.6 TL = 257.1~ 280.3~297.4 [Lens Data] m r d νd nd 1 257.902 2.000 35.7 1.90265 2 97.65911.000  82.6 1.49782 3 −314.680 0.100 4 79.130 10.000  82.6 1.49782 52088.342 D1 6 123.691 5.763 33.3 1.80610 7 −77.164 2.000 65.4 1.60300 869.162 5.674 9 −187.746 2.000 42.7 1.83481 10 35.095 4.370 23.8 1.8466611 112.202 6.514 12 −44.561 1.800 42.7 1.83481 13 581.099 D2 14 97.5744.250 60.3 1.62041 15 −88.827 0.100 16 84.452 2.000 31.3 1.90366 1732.485 5.655 60.3 1.62041 18 −240.662 D3 19 0.000 3.000 Aperture stop S20 −57.650 1.500 50.3 1.71999 21 62.520 3.298 42.7 1.83481 22 −209.983D4 23 91.072 5.000 70.3 1.48749 24 −99.387 2.087 25 62.240 2.000 32.41.85026 26 35.334 5.183 82.6 1.49782 27 602.097 17.041  28 42.594 4.26327.6 1.75520 29 −76.745 1.500 40.7 1.88300 30 33.248 BF [Focal Length ofLens Group] Lens group First surface Focal length First lens group 1142.392 Second lens group 6 −31.449 Third lens group 14 56.441 Fourthlens group 20 −152.964 Fifth lens group 23 117.618

In Example 5, the axial air distance D1 between the first lens group G1and the second lens group G2, the axial air distance D2 between thesecond lens group G2 and the third lens group G3, the axial air distanceD3 between the third lens group G3 and the aperture stop S which movestogether with the fourth lens group G4, the axial air distance D4between the fourth lens group G4 and the fifth lens group G5, and theback focus BF change upon zooming. Table 14 shows the values of thevariable distances D1 to D4 and the back focus BF at each focal lengthin the wide-angle end state, the intermediate focal length state and thetelephoto end state upon focusing on infinity.

TABLE 14 [Variable Distance Data] Intermediate Wide−angle focal lengthTelephoto end state state end state f 103.0~ 200.0~ 388.0 D1 17.898~41.055~ 58.209 D2 34.045~ 20.108~ 2.000 D3 6.078~ 21.988~ 29.609 D420.042~ 8.963~ 8.026 BF 71.0~ 80.1~ 91.5

Table 15 shows a value corresponding to each conditional expressionaccording to Example 5.

TABLE 15  (1) f1/(−f2) = 4.53  (2) f1/f3 = 2.52  (3) f3/(−f4) = 0.37 (4) (−f4)/f5 = 1.30  (5) f1/(−f2) = 4.53  (6) f3/f5 = 0.48  (7)f1/(−f4) = 0.93  (8) f2/f4 = 0.21 (24) f1/(−f2) = 4.53 (25) f1/f3 = 2.52(26) f3/(−f4) = 0.37 (27) (−f4)/f5 = 1.30

As a result, the zooming optical system ZL5 of Example 5 satisfies allthe conditional expressions (1) to (8) and (24) to (27).

FIG. 19A is a set of graphs showing various aberrations of Example 5upon focusing on infinity in the wide-angle end state, FIG. 20A is a setof graphs showing various aberrations of Example 5 upon focusing oninfinity in the intermediate focal length state, and FIG. 21A is a setof graphs showing various aberrations of Example 5 upon focusing oninfinity in the telephoto end state. FIG. 19B is a set of graphs showingcoma aberration of Example 3 when image blur is corrected upon focusingon infinity in the wide-angle end state (shift amount ofvibration-isolating lens group=−0.419), FIG. 20B is a set of graphsshowing coma aberration when image blur is corrected upon focusing oninfinity in the intermediate focal length state (shift amount ofvibration-isolating lens group=−0.538), and FIG. 21B is a set of graphsshowing coma aberration when image blur is corrected upon focusing oninfinity in the telephoto end state (shift amount of vibration-isolatinglens group=−0.682). As each graph showing aberrations clarifies, inExample 5, the zooming optical system has an excellent image formingperformance, where various aberrations are corrected well in each focallength state from the wide-angle end state to the telephoto end state.

The anti-reflection film used for the zooming optical systems ZL (ZL1 toZL5) according to Example 1 to Example 5 will now be described. As FIG.26 shows, the anti-reflection film 101 according to each example isconstituted by seven layers (first layer 101 a to seventh layer 101 g),and is formed on the optical surface of an optical member 102 of thezooming optical system ZL.

The first layer 101 a composed of aluminum oxide is deposited by avacuum deposition method. The second layer 101 b composed of a mixtureof titanium oxide and zirconium oxide is deposited on the first layer101 a by the vacuum deposition method. Then the third layer 101 ccomposed of aluminum oxide is deposited on the second layer 101 b by thevacuum deposition method, and the fourth layer 101 d composed of amixture of titanium oxide and zirconium oxide is deposited on the thirdlayer 101 c by the vacuum deposition method. Then the fifth layer 101 ecomposed of aluminum oxide is deposited on the fourth layer 101 d by thevacuum deposition method, and the sixth layer 101 f composed of amixture of titanium oxide and zirconium oxide is deposited on the fifthlayer 101 e by a vacuum deposition method. Then the seventh layer 101 gcomposed of a mixture of silica and magnesium fluoride is deposited onthe sixth layer 101 f by a wet process. Thereby the anti-reflection film101 of each example is formed.

To form the seventh layer 101 g, a sol-gel method, which is a type ofwet process, is used. The sol-gel method is a method of generating afilm by coating sol, which is an optical thin film material, on anoptical surface of an optical member, depositing a gel film thereon,dipping the optical surface in liquid, and increasing the temperature ofthe liquid and pressure to be at or more than the critical state, so asto vaporize and dry the liquid. The wet process is not limited to thesol-gel method, but may be a method of acquiring a solid film bypassingthe gel state.

As described above, the first layer 101 a to the sixth layer 101 f ofthe anti-reflection film 101 are formed by electron beam deposition,which is the dry process, and the seventh layer 101 g, which is theoutermost layer (top layer), is formed by the wet process using the solsolution prepared by the hydrofluoric acid/magnesium acetate method.

Now a procedure to form the anti-reflection film 101 having thisconfiguration will be described. First the aluminum oxide layer to bethe first layer 101 a, the titanium oxide-zirconium oxide mixed layer tobe the second layer 101 b, the aluminum oxide layer to be the thirdlayer 101 c, the titanium oxide-zirconium oxide mixed layer to be thefourth layer 101 d, the aluminum oxide layer to be the fifth layer 101e, and the titanium oxide-zirconium oxide mixed layer to be the sixthlayer 101 f are sequentially formed on the film deposition surface ofthe lens (optical surface of the optical member 102) using a vacuumdeposition apparatus. After removing the optical member 102 out of thevacuum deposition apparatus, the binder component-added sol solution,prepared by the hydrofluoric acid/magnesium acetate method, is coated onthe optical surface by a spin coat method, whereby a layer composed of amixture of silica and magnesium fluoride to be the seventh layer 101 gis formed. The reaction formula in this preparation performed by thehydrofluoric acid/magnesium acetate method is shown below.

2HF+Mg(CH₃COO)²→MgF₂+2CH₃COOH

For the sol solution used for the film deposition, raw materials aremixed first, and high temperature heating and aging processing isperformed on the mixture at 140° C. for 24 hours in an autoclave beforebeing used for film deposition. After the deposition of the seventhlayer 101 g is completed, the optical member 102 is heated at 160° C. inair for one hour, and processing completes. In concrete terms, severalnm to several dozens of nm sized MgF₂ particles are formed by thesol-gel method, and several of these particles are gathered respectivelyand secondary particles are formed, and the seventh layer 101 g isformed by the deposition of these secondary particles.

The optical performance of the anti-reflection film 101 formed like thiswill be described with reference to the spectral Characteristics shownin FIG. 27. FIG. 27 shows the spectral Characteristics when lightvertically enters the anti-reflection film 101 designed under theconditions shown in the following Table 16 (reference wavelength λ is550 nm). In Table 16, Al₂O₃ indicates aluminum oxide, ZrO₂+TiO₂indicates the titanium oxide-zirconium oxide mixture, and SiO₂+MgF₂indicates the mixture of silica and magnesium fluoride, and shows therespective design values when the refractive indexes of the substrateare 1.46, 1.62, 1.74 and 1.85 (reference wavelength λ is 550 nm).

TABLE 16 Optical Optical Optical Optical Refractive Film Film Film FilmSubstance Index Thickness Thickness Thickness Thickness Medium Air 1.00Seventh SiO₂ + MgF₂ 1.26 0.275λ 0.268λ 0.271λ 0.269λ layer Sixth ZrO₂ +TiO₂ 2.12 0.045λ 0.057λ 0.054λ 0.059λ layer Fifth Al₂O₃ 1.65 0.212λ0.171λ 0.178λ 0.162λ layer Fourth ZrO₂ + TiO₂ 2.12 0.077λ 0.127λ 0.130λ0.158λ layer Third Al₂O₃ 1.65 0.288λ 0.122λ 0.107λ 0.080λ layer SecondZrO₂ + TiO₂ 2.12 0 0.059λ 0.075λ 0.105λ layer First Al₂O₃ 1.65 0 0.257λ0.030λ 0.030λ layer Refractive 1.46 1.62 1.74 1.85 index of substrate

As shown in FIG. 27, the reflectance is controlled to 0.2% or less inthe entire region of wavelengths 420 nm to 720 nm.

In the zooming optical system ZL1 of Example 1, the refractive index ofthe plano-convex lens L54 is 1.51742, hence the anti-reflection filmcorresponding to 1.46 of the refractive index of the substrate can beused for the image side lens surface of the plano-convex lens L54. Therefractive index of the biconvex lens L55 is 1.64769, hence theanti-reflection film corresponding to 1.62 of the refractive index ofthe substrate can be used for the object side lens surface of thebiconvex lens L55.

In the zooming optical system ZL2 of Example 2, the refractive index ofthe negative meniscus lens L53 is 1.84666, hence the anti-reflectionfilm corresponding to 1.85 of the refractive index of the substrate canbe used for the image side lens surface of the negative meniscus lensL53. The refractive index of the biconvex lens L61 is 1.72825, hence theanti-reflection film corresponding to 1.74 of the refractive index ofthe substrate can be used for the object side lens surface of thebiconvex lens L61.

In the zooming optical system ZL3 of Example 3, the refractive index ofthe negative meniscus lens L54 is 1.84666, hence the anti-reflectionfilm corresponding to 1.85 of the refractive index of the substrate canbe used for the image side lens surface of the negative meniscus lensL54. The refractive index of the biconvex lens L61 is 1.75520, hence theanti-reflection film corresponding to 1.74 of the refractive index ofthe substrate can be used for the object side lens surface of thebiconvex lens L61.

In the zooming optical system ZL4 of Example 4, the refractive index ofthe negative meniscus lens L54 is 1.84666, hence the anti-reflectionfilm corresponding to 1.85 of the refractive index of the substrate canbe used for the image side lens surface of the negative meniscus lensL54. The refractive index of the biconvex lens L61 is 1.71736, hence theanti-reflection film corresponding to 1.74 of the refractive index ofthe substrate can be used for the object side lens surface of thebiconvex lens L61.

In the zooming optical system ZL5 of Example 5, the refractive index ofthe positive meniscus lens L53 is 1.49782, hence the anti-reflectionfilm corresponding to 1.46 of the refractive index of the substrate canbe used for the image side lens surface of the positive meniscus lensL53. The refractive index of the biconvex lens L54 is 1.75520, hence theanti-reflection film corresponding to 1.74 of the refractive index ofthe substrate can be used for the object side lens surface of thebiconvex lens L54.

By applying the anti-reflection film 101 of each example to the zoomingoptical system ZL (ZL1 to ZL5) according to Examples 1 to 5respectively, a zooming optical system having high optical performanceto further decreases ghosts and flares, an optical apparatus includingthis zooming optical system, and a zooming method for the zoomingoptical system, can be provided.

The anti-reflection film 101 may be used as an optical element disposedon the optical surface of a plane parallel plate, or may be disposed onthe optical surface of a lens formed in a curved shape.

A modification of the anti-reflection film 101 will be described next.The anti-reflection film according to this modification is constitutedby five layers, and is constructed under the following conditions inTable 17. The above mentioned sol-gel method is used to form the fifthlayer. Table 17 shows the design values when the reference wavelength λis 550 nm and the refractive index of the substrate is 1.52.

TABLE 17 Optical Refractive film Substance index thickness Medium Air1.00 Fifth Mixture of silica and magnesium 1.26 0.269λ layer fluorideFourth Titanium oxide-zirconium oxide 2.12 0.043λ layer mixture ThirdAluminum oxide 1.65 0.217λ layer Second Titanium oxide-zirconium oxide2.12 0.066λ layer mixture First Aluminum oxide 1.65 0.290λ layerSubstrate BK7 1.52

FIG. 28 shows the spectral characteristics when light vertically entersthe anti-reflection film of the modification. As FIG. 28 shows, thereflectance is controlled to 0.2% or less in the entire region ofwavelengths 420 nm to 720 nm. FIG. 29 shows the spectral characteristicsin the case when the incident angle is 30°, 45° or 60°.

For comparison, FIG. 30 shows the spectral characteristics when lightvertically enters a multilayered wideband anti-reflection film, which isformed only by a dry process, such as a conventional vacuum depositionmethod, and is constructed under the following conditions in Table 18.FIG. 31 shows the spectral characteristics in the case when the incidentangle is 30°, 45° or 60°.

TABLE 18 Optical Refractive film Substance index thickness Medium Air1.00 Seventh MgF₂ 1.39 0.243λ layer Sixth Titanium oxide-zirconium oxide2.12 0.119λ layer mixture Fifth Aluminum oxide 1.65 0.057λ layer FourthTitanium oxide-zirconium oxide 2.12 0.220λ layer mixture Third Aluminumoxide 1.65 0.064λ layer Second Titanium oxide-zirconium oxide 2.120.057λ layer mixture First Aluminum oxide 1.65 0.193λ layer SubstrateBK7 1.52

The comparison of the spectral characteristics of the modification shownin FIG. 28 and FIG. 29 with the spectral Characteristics of the priorart shown in FIG. 30 and FIG. 31 clearly demonstrates that thereflectance of the anti-reflection film according to the modification islow.

As described above, according to these examples, a high performanceoptical system that has a camera shake correction mechanism and that canfurther decrease ghosts and flares, an optical apparatus including thiszooming optical system, and a zooming method for the zooming opticalsystem, can be provided.

EXPLANATION OF NUMERALS AND CHARACTERS

-   -   ZL (ZL1 to ZL5) zooming optical system    -   G1 first lens group    -   G2 second lens group    -   G3 third lens group    -   G4 fourth lens group    -   G5 fifth lens group    -   S1 aperture stop    -   1 camera (optical apparatus)

1. A zooming optical system comprising, in order from an object: a firstlens group having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, wherein, upon zooming,distances between adjacent lens groups of the first to the fifth lensgroups change respectively, and the following conditional expression issatisfied:9.6<ft/(−f2)<20.0 where ft: denotes a focal length of the zoomingoptical system in a telephoto end state, and f2 denotes a focal lengthof the second lens group.
 2. The zooming optical system according toclaim 1, wherein the following conditional expression is satisfied:3.9<ft/(−f4)<8.8 where f4 denotes a focal length of the fourth lensgroup.
 3. The zooming optical system according to claim 1, wherein thesecond lens group is fixed with respect to an image plane upon zooming.4. The zooming optical system according to claim 1, wherein thefollowing conditional expression is satisfied:0.8<(−f4)/f5<1.8 where f4 denotes a focal length of the fourth lensgroup, and f5 denotes a focal length of the fifth lens group.
 5. Thezooming optical system according to claim 1, wherein the followingconditional expression is satisfied:0.3<(−f2)/f5<0.8 where f5 denotes a focal length of the fifth lensgroup.
 6. The zooming optical system according to claim 1, wherein thefollowing conditional expression is satisfied:1.9<f1/f5<3.2 where f1 denotes a focal length of the first lens group,f5 denotes a focal length of the fifth lens group.
 7. The zoomingoptical system according to claim 1, wherein the following conditionalexpression is satisfied:0.44<(−f2)/f3<0.86 where f3 denotes a focal length of the third lensgroup.
 8. The zooming optical system according to claim 1, wherein thefollowing conditional expression is satisfied:0.18<f3/(−f4)<0.92 where f3 denotes a focal length of the third lensgroup, and f4 denotes a focal length of the fourth lens group.
 9. Thezooming optical system according to claim 1, wherein the followingconditional expression is satisfied:0.10<f3/f5<1.06 where f3 denotes a focal length of the third lens group,and f5 denotes a focal length of the fifth lens group.
 10. The zoomingoptical system according to claim 1, wherein the following conditionalexpression is satisfied:0.70<f1/(−f4)<2.55 where f1 denotes a focal length of the first lensgroup, and f4 denotes a focal length of the fourth lens group.
 11. Thezooming optical system according to claim 1, wherein the followingconditional expression is satisfied:0.11<f2/f4<0.62 where f4 denotes a focal length of the fourth lensgroup.
 12. An optical apparatus for forming an object image on apredetermined image plane, comprising the zooming optical systemaccording to claim
 1. 13. A manufacturing method for a zooming opticalsystem, comprising: arranging, in order from an object, a first lensgroup having positive refractive power, a second lens group havingnegative refractive power, a third lens group having positive refractivepower, a fourth lens group having negative refractive power and a fifthlens group having positive refractive power, wherein, upon zooming,distances between adjacent lens groups of the first to the fifth lensgroups change respectively, and the following conditional expression issatisfied:9.6<ft/(−f2)<20.0 where ft: denotes a focal length of the zoomingoptical system in a telephoto end state, f2 denotes a focal length ofthe second lens group.